Yes, it is possible. Are you going to pay for the development, licencing, lawyers, etc...?
I have no idea what you are talking about with your second quetion. I think it was Compaq that wrote their own IBM PC BIOS through reverse engineering, thus creating the clone market for IBM-PCs. Microsoft "wrote" MS-DOS, it was based on QDOS, for the IBM PC. Dr.DOS and others were third pary clones of MS-DOS. Basic has nothing to do with it.
erm, I suppose someone could write their own Amiga compatable ROM code. Thus, eliminating the need for Real legal Amiga ROM chips. I think there is an AROS bounty for something like this. Not to menion AROS is pretty much what you are talking about in using your example of the IBM-PC. It is a clean room implementation of Amiga OS. QDOS was a clean room implemnetation of CP/M, which IBM looked at for an OS first then turned to MS.
http://en.wikipedia.org/wiki/IBM_PCIt probably will violate the agreement if Hyperion where to do this. If not violate, at least be beyond the scope of the agreement and licence.
Oh, AROS has a bounty for integrating UAE. As to PPC, I would think that, unlike 68K programs, PPC programs would not run too fast emulated.
You do realize what you are asking is like asking for world peace and has been discussed to death.
:horse: