1 - I don't think the full print volume is known. I believe it is not until the beta kits are sent out that Rinnovated is going to do some large scale print testing. Right now, they are doing small prints for speedy testing. Gonna have to wait on a good answer for your first question.

2 - Aperture is still a concern, but at the moment, small and mid sized prints do not seem to be a challenge for the peachy. Shine distance is also currently not an issue. The issues you are worried about will only apply, it seems, to large prints. But we won't know about those limitations until large scale prints are being tested. So, it looks like you will have to wait a bit on this answer too.

3 - I believe the peachy is compatible with a 24 bit sound card, but it will not give it better resolution, because the signal from your computer is modulated after the fact.

4 - I wish I knew, and if I had to wager a guess, I would guess that the very first batch, of multiple batches of betas, will ship at the end of the month, or early march. I am not affiliated, this is not an official answer