i cant claim to be an expert on this although i have used both in pcs and checked into useing either with my 3000 if i got a mediator for it. but here goes:
1:possibly if enough people were to request it
2:not that i know of
3:yes but not that the drivers support
5:vd5 works fine if you have one id keep it. if the power and fan are really objectionable and you got a line on a vd3 go for it.