I'm going to assume your putting a V-8 in. I just put a LS-1 in a S-10 Blazer. The easy way is a kit. That can be bought for V-8 conversion. It was about $350.00 It came with motor mounts and transmission crossmember with mounts. This is the best and safe way to go.
It can be done.
You can if it has the Chevy bolt pattern.
You throw alot of time and money at it to build a custom set up
You can substitute a 400 for a 350. Get one with the same length tailshaft as the 350 you are replacing. You'll need the correct driveshaft yoke, and the kickdown is different.
yes a 350 turbo converter will fit a 400 turbo and vice versa
There's only one type of 400 turbo.
A turbo 400 is an automatic transmission, so yes, it will shift itself, unless someone has put in a manual valve body or transmission brake -- both of which are mainly used by racers.
No it will NOT interchange. The 350 and 400 turbo are actually VERY different transmissions.
NO.
NO it will not.
no
As long as it has the Chevy bolt pattern, yes.