The commentarial interpretation of parimukha (translated above as “in front”) is that it refers to the tip of the nose or perhaps the upper lip. The problem is there is not much Canonical support for this. Some meditation movements have a wider interpretation, such as the Mahāsi tradition where they focus on the abdomen.
Both Bhante Sujato (see “History of Mindfulness”, pp. 109-110) and Ven. Analayo (“Satipaṭṭhāna”, pp.108-109) dispute that parimukha can be pinned down in such a narrow way. I think they are probably right. To me the idea of “establishing mindfulness in front” is clear enough. In the context of ānāpānasati it probably just means being aware of the breath in the present moment, and not relating it to any specific physical location. As your meditation deepens, if you attend to it, you may very well notice that you are in fact aware of the breath at the tip of the nose. (And it may be that this is where the commentarial interpretation comes from.) But usually there is no particular reason why you would focus on this. Ānāpānasati is, after all, breath meditation, not body meditation.
Establishing mindfulness in the right way requires presence of mind and sufficient clarity. You are then ready to focus on the breath.
Yes, you need a high level of sīla for the sequence in AN 10.2 to be automatic. But as always it is a gradual thing. The better your sīla, the further up the sequence you will tend to go. This tells you something the importance of sīla for meditation practice.
It is important to bear in mind that sīla in Buddhism is much wider than what we normally mean by “morality”. I sometimes like to regard it as character development. In other words, it is not just about how we act and speak, but also about how we think and even how we perceive the world. When all of this is developed according to Dhamma - less anger and desire, more kindness and compassion - then the meditation develops accordingly.
The exertion of volition occurs mostly in regard to sīla. This may include the early stages of meditation, because you may need to exert a bit of will to avoid the hindrances arising in the mind. But this is a very minor exertion of the will. If you have prepared the mind well, it is almost automatic.
Probably both. I think willpower may take you some of the way, but eventually it will block you from going further. If you have made a habit of it, it may be difficult to give it up as your meditation deepens. Many meditators - good meditators - say they were not even aware they were using willpower. It tends to be very subtle. I think it is good to get out of the habit as soon as possible.
Anyway, I like the idea of it all being dhammatā, “natural”. It’s just so appealing. You live well and with kindness. But when you sit down to meditate, all you do is relax and enjoy yourself. This is part of what makes the path so worthwhile. You are not only allowed to enjoy yourself, you are encouraged to do so! Profound happiness is an indispensable aspect of the path.
