I have found a couple out there, but these are expensive and hard to get. Looking for one that won't break the bank. The Wiselite looks perfect, but I don't think those are available anymore.
Yes, and no. The first one that comes to mind is a PPS-43C that has either been converted to a rifle by replacing the stock and adding a 16" barrel, or converted by just getting the stock and SBRing it.
I know of no commercial 7.62x25 carbines, but I have heard that AR uppers for it were made at some point.
I wouldn't mind one myself. That round is a little powerhouse and would be pretty sweet in a rifle.