TH350, unless you want an overdrive, then, I would go with the 700R4.
yes
Yes it will, it is the same bolt pattern.
Dextron.
It depends on the transmission and any modifications to the engine.
Yes it will, It should already have a small block Chevy in it , if it's a V8.
The 400 Chevy small block motor should have approximately 390 horse power. It should have 427 foot pounds of torque.
If it's a 350 from a Chevy, yes.
A Nissan 300ZX? No
You will need to remove the transmission.
It would never hold together.....
usually around 1200-1300 rpm
Yes you can, but a 350 is a small block, not a big block.