Mindfulness with Pride, Anger, Hatred

1. I'm still debating or trying to understand whether one should experience fully all emotions and states or whether one should apply antidotes to certain states when they arise. Generally speaking, which is the case? Which would correspond to being fully mindful?

Both can be done fully mindful. If you experience fully all emotions, you can be mindful during that experience. If you apply antidotes to certain states when they arise, you can be mindful during these experiences. Just remember, when you note an emotion/feeling/thought/etc., let go of it and return to your meditation object (in your case the breath). Be mindful of "things" that distract you away from the meditation object, so that whenever you notice that your mind wandered away from the meditation object, return back to it and stay with it.

2. I am having extreme difficulty with anger and pride when they arise, as when they do, I seem to be unable to keep a compassionate attitude. Basically these states seem to change my mood and outlook when they occur, and I have difficulty experiencing them without doing this.

If you're having difficulties with anger and pride, stop the arising of anger and pride. How? Observe as precisely as you can how anger and pride arise. If you'll observe precisely enough, you'll see the cause of both. Remove the cause, and both will be removed. In order to be able to see the cause, you must train your mind until you reach a point where you can be focused on your meditation object (in your case the breath) without interruptions.

3. Lastly, I'm unsure whether this is related as well but I noticed I have a much easier time doing mindfulness when I'm basically curious and aware of everything arising rather than re-focusing on the breath. Any ideas on that topic?

Why do you have a much easier time doing mindfulness when you're curious and aware of everything arising? What bothers you when you're re-focusing on the breath? Answer it yourself and you'll know what you should work on.

Nonetheless, when you see something arising, you should note it, and then let go of it by re-focusing back on the breath. Note and let go by going back to your object of meditation (in your case the breath). You should train your mind like that. With practice, you'll be able to be focused on the breath without interruptions. You'll need this level of concentration later to see the main cause of phenomena arising in your mind (in your case, for example, anger and pride).

How you practise is your choice.

In formal Buddhism, having 'right mindfulness' means to apply antidotes to certain unskilful states when they arise. This is described in the 6th factor of the Noble Eightfold Path (Right Effort) and in suttas such as the Dvedhavitakka Sutta.

However, this can cause stress if the unskilful states are powerful. Therefore, sometimes we must simply be patient with unskilful states until they subside or until we learn the lesson we need to learn from them.

And what, monks, is right effort? (i) There is the case where a monk generates desire, endeavors, activates persistence, upholds & exerts his intent for the sake of the non-arising of evil, unskillful qualities that have not yet arisen. (ii) He generates desire, endeavors, activates persistence, upholds & exerts his intent for the sake of the abandonment of evil, unskillful qualities that have arisen. (iii) He generates desire, endeavors, activates persistence, upholds & exerts his intent for the sake of the arising of skillful qualities that have not yet arisen. (iv) He generates desire, endeavors, activates persistence, upholds & exerts his intent for the maintenance, non-confusion, increase, plenitude, development, & culmination of skillful qualities that have arisen: This, monks, is called right effort. Magga-vibhanga Sutta: An Analysis of the Path

1-I'm still debating or trying to understand whether one should experience fully all emotions and states or whether one should apply antidotes to certain states when they arise. Generally speaking, which is the case? Which would correspond to being fully mindful?

You can try to experience fully all emotions and states as you apply an antidote. You wouldn't have to stop being mindful in order to do this other "antedote" practice, you can be mindful of the other practice too. When we "experience fully all emotions and states" moment by moment, that is mindfulness.

2-I am having extreme difficulty with anger and pride when they arise, as when they do, I seem to be unable to keep a compassionate attitude. Basically these states seem to change my mood and outlook when they occur, and I have difficulty experiencing them without doing this.

You can be compassionate towards yourself as you are mindful of your reactions to attempting to be compassionate to yourself. If you see you are suffering, tell yourself "it's okay". Be nurturing to yourself and be mindful of your reactions to your own compassion being aimed at you. Maybe you dont feel your worthy of compassion grom yourself. Then tell yourself "Its Okay".

3-Lastly, I'm unsure whether this is related as well but I noticed I have a much easier time doing mindfulness when I'm basically curious and aware of everything arising rather than re-focusing on the breath. Any ideas on that topic?

Always go back to the breath. This is what grounds the practice and facilitates peace. The breath gives the practice a home.

You will grow more and more weary of everything arising, if you are practicing correctly.