Maintaining the emotional state achieved in meditation through the rest of the day

As you move further on the path you tend to move more and more into the four heavenly abodes http://en.wikipedia.org/wiki/Brahmavihara. With Ken Wilber terminology, there is stages and there are states, states are temporary whereas when you reach a stage you stay there. When close to moving on the next stage you more frequently experience higher states. Any state can be reached temporarily from any stage though.

Bliss can be both be a hindrance and an inspiration in meditation, we tend to want it again and cling to it. Because of that glimpses of realization early on in the practice may be problematic. This is natural, all beings want to be happy.

May you be happy, go on and get back to the practice.

One of the nature of our self is that we are not in absolute control. Some presentness due to meditation may persist with a higher degree of probability but there is not saying that something or mood will not occur for certainty. Nor there is any technique to prevent them with absolute certainty.

Basically what you can do is if you are waiting and some times not doing anything make it a chance to do some Breath meditation (without letting others know you are doing it as people might start looking at you funny if they get to know). This will give you a boost to keeping up the presentness with a higher degree of probability.

This pleasurable state that you are attaining during meditation is simply the result of concentration. These states can be developed in different directions within the Buddhist path, but if their place is not properly understood, they can in time become a hindrance.

This bliss isn't enlightenment unfortunately. The goal of Buddhist meditation is to attain clarity of mind and concentration in order to see that reality is impermanent, unable to give us stable and lasting pleasure, and non-self. When these are fully realized, the mediator will be able to at least temporarily let go totally of all attachment and experience the happiness of Nibbana (or Nirvana in Sanskrit), a happiness that is totally distinct from everything else in this world. When this is realized repeatedly, one can eventually become a fully enlightened Arahat, in which one is perfectly happy at all times because has no attachment and is content with whatever comes to be.

In order to progress towards this enlightenment you must understand that these states are a step on the path, and that they are a powerful tool, but not a goal in and of themselves. At this stage you have a choice in how to continue in practice. Option one is to continue to practice meditation the way you are (although there will come a point when the music will prevent deeper concentration, but if you really want to, continuing it for now isn't the worst thing in the world). It is possible to develop this into a powerful state of concentration and peace called Jhana in which the perception of the body totally vanishes. A good book explaining how to do this (you might be able to find it in pdf form here: http://www.dhammatalks.net/ ) is the book Mindfulness, Bliss, and Beyond by Ajahn Brahm. He has a lot of other books on practicing the Jhanas as well.

Eventually, even with attaining jhanas, you will need to also develop a quality of mind called Vipassana. You can switch over to practicing Vipassana meditation now as well, or you can switch later. There are several different styles of Vipassana meditation. There is the Mahasi Sayadaw tradition of Vipassana meditation, the Goenka tradition, and some of the practices of the Thai forest tradition such as meditation as taught by the Ven. Thannisaro Bhikku can be classefied as Vipassana meditation.

One of the best resources for learning the Mahasi Sayadaw style meditation can be found here: https://www.youtube.com/watch?v=hLvU7ppM4vE&list=PLAFC00C07636BE277 It is taught by the Ven. Yuttadhammo, an excellent monk who I can personally attest to as having tremendous wisdom and teaching ability. I consider myself to be a follower of his even though I myself don't practice the Mahasi Sayadaw method, I find his advice to be spot on. I would also highly recommend watching this video of his as well: https://www.youtube.com/watch?v=fjUkzRcNhK8

You can find some writings of Ajahn Thanisarro on that dhammatalks.net site. He can also be quite helpful although he isn't very explicit in talking about vipassana specifically, if you want to continue your concentration style practice this is good because he incorporates both aspects of teaching. He has a book of meditation instructions here: http://www.dhammatalks.org/Archive/Writings/EachAndEveryBreath_v130117.pdf