How do Protestants in general respond to these points concerning them?

Full Disclaimer: I am an Eastern Orthodox Christian who is a former Protestant Christian. I have addressed how Protestants might respond to these points, with the understanding that Protestants are a very broad group with many differing beliefs on these issues. With that said, these responses must necessarily be broad and somewhat varied.

According to Whom/What?

First we need to have a brief discussion on authority. For Protestants, sola scriptura is a central tenet of the faith, i.e. scripture alone. Different groups understand this differently, however.

For more traditional Protestants, who for lack of a better term are more "historically rooted" (most Lutherans, some Anglicans, some Reformed, etc.), sola scriptura does not mean following the Bible subjectively in such a way that completely ignores the voices of the past (e.g. early Church Fathers, the decisions of Church councils, etc.). Indeed, the initial intention of the Protestant Reformers did not preclude ignoring patristic consensus and the traditions of the historic catholic Church. James C. Payton, Jr., a Protestant scholar, addresses this in his book Getting the Reformation Wrong: Correcting Some Misunderstandings.

For most non-traditional Protestants, who for lack of a better term I will refer to as "historically disconnected" (those who reject most or all historic traditions, e.g. Baptists, mainstream evangelicals, most 'non-denominational' churches, Pentecostals, etc.), they claim to live by the guidance of scripture alone under the direct influence of the Holy Spirit (despite the fact that there is no Protestant consensus on much anything other than the fact that scripture is the only authority, which I personally find somewhat ironic). This is a purely subjective understanding of authority that gives little to no authority to traditions or voices outside of one's denominational organization, sometimes even ignoring the teachings of previous generations of leaders within the same organization and/or local church.

Many Protestants will fall in between these two extremes, but I had to create some categories for the sake of making a point about authority. In contrast, Eastern Orthodox Christians believe that Holy Tradition is the source of authority, in which scripture plays the preeminent role. It should also be noted that Roman Catholics also believe the Pope has the authority to interpret scripture and they include the deuterocanonical works in their canon (and in some cases consider the Latin Vulgate to have more authority than other manuscripts), and Eastern Orthodox Christians have several other apocryphal writings and are much looser on their definition of the canon (and believe the Septuagint is the authoritative Old Testament and apocryphal text).

This fundamental disagreement on authority is an important factor in all subsequent theological discussion, since the two have very different beliefs about authority and who/what can be appealed to in defense or refutation of a practice or belief.

Apostolic Succession

There actually are Protestants who believe that apostolic succession is important, such as some conservative Anglican groups. But the vast majority do not. Of those who reject apostolic succession, they generally attack it from one of three angles:

1. Historical fallacy - Things got pretty convoluted in the early Church and it is pretty hard to back up the claim that there is a clear, delineated succession from the apostles through the present time. Protestants who take this approach will attempt to use historical evidence (or the lack thereof) to suggest that the succession was broken at some point in history, often by claiming that this process became corrupt through later practices (e.g. the Investiture Controversy and similar historical corruptions), or by claiming that there never was valid succession in the first place and it was only invented by corrupt leaders to establish power and control (Anabaptists are particularly fond of this stance).
2. No longer relevant - Some "historically connected" Protestants actually will acknowledge the value of apostolic succession in early Church history, specifically the role it played in the defeat of Gnosticism and formation of the New Testament canon within the Christian Church. These Protestants may combine this perspective with the first, claiming that it was originally valid but later corrupted. Others will grant that the Eastern Orthodox or Roman Catholic Church are still in apostolic succession but it is no longer important since Protestants believe that these churches have departed from the teachings of scripture.
3. Irrelevant - This is the general stance of "historically disconnected" traditions. Since apostolic succession is not explicitly taught in the bible, it is therefore irrelevant (this is actually the refutation of most traditions for "historically disconnected" Protestants, due largely in part to the many individualistic biases that they hold thanks to the Enlightenment and the French and American revolutionary wars).

The Sacraments as Means of Grace

As an Orthodox Christian, I have to take issue with your statement that the sacraments are "the ways specially ordained by God for conveying the Holy Spirit." The statement is not entirely wrong, but it depends largely upon which of the sacraments is being referenced. I would reword that to say that they convey grace. I will proceed by operating under this revised definition.

This is really not a fair charge: Protestants are divided on this issue. Most of the "historically connected" Protestants do indeed view the sacraments as means of grace. Conversely, the "historically disconnected" Protestants do not. Those that do are divided on the number of sacraments and how they believe the sacraments convey grace (using Aristotelian metaphysical philosophical terms to explain their differences, thanks to the influence of Scholasticism in Western Christianity), but they agree that grace is conveyed nonetheless.

Those that disagree (not just the "historically disconnected," some "historically connected" Protestants are also in this camp) will usually take one of three approaches:

1. Philosophical/Pagan-influenced - Some Protestants recognize that most sacramental controversies center on the language of Aristotelian metaphysics and reject the sacraments as an altogether philosophical argument that has no bearing on the reality of their substance/essence. Others further argue that the philosophical concept of sacraments existed in paganism and thus the entire notion is pagan.
2. Rationalism - Using Holy Communion (i.e. the "Eucharist") as an example, these Protestants would argue that since the elements clearly do not change from an empirical/scientific standpoint, the entire notion of sacraments is absurd (again we can see the influence of the Enlightenment).
3. Irrelevant - It's not explicitly mentioned in the bible, therefore it's wrong (often commingled with rationalism on this issue).

The Protestant Disadvantage

The argument here seems to be that since many Protestants reject apostolic succession and the belief that sacraments convey grace, they are at a disadvantage compared to Eastern Orthodox Christians (and presumably also Roman Catholic Christians).

Since I've demonstrated that not all Protestants reject these beliefs, this syllogism is actually false. However, for the sake of providing a satisfactory answer, let me address this argument as it applies to those Protestants who do reject both practices (for whatever reason).

These Protestants would not consider themselves to be at a disadvantage, in fact they would assert that the opposite is true. Since they do not believe these practices are scriptural nor relevant in the contemporary Church, they would argue that they actually lead people away from God. There's not much more I can say on this one, especially since by and large it is a false syllogism.

From an Orthodox perspective, Protestants are not at a disadvantage for the rejection of any specific beliefs or practices, but rather their attitude towards the historic Christian faith in general. The "family tree" of Christianity has been around a lot longer than Protestants have, but this branch came along and now claims it's the whole tree! Claiming to be the entire tree while cutting off its trunk and roots is a recipe for disaster, and it's also very arrogant. Few Orthodox Christians would ever make a sweeping statement about the eternal destiny of all Protestants, yet many Protestants routinely claim that all Catholics (and Orthodox) are going to hell. So when we seem a little snarky, please understand that we're often responding to the arrogance inherent in Protestantism. Even so, this is a failure on our part to continue to model true humility to Protestants, and for that I apologize. Please pray for me.

In conclusion, I've addressed each of the three points as well as the nature of authority, which I believe is an important underlying issue in the discussion of any belief or practice within Christianity.