Usually 15 from the factory, but some Jeeps could have gotten an aftermarket 20, 21 or 24 gallon tank
15 gal from the factory, but an aftermarket 20, 21 or 24 gallon tank can be swapped in.
Yes
No, there are too many differences
Practical answer is no
yes even the yj top will fit also
If you haven't seen it already, this may help. http://www.offroaders.com/info/tech-corner/project-cj7/project-cj7-heater.htm
You've got to drop the fuel tank, or cut an access opening in the body tub over the fuel tank inlet. Besides the sending unit, you will almost certainly need the lock ring that attaches it to the tank also. There is the distinct possiblity the rust in that area is so bad the tank will need to be replaced.
6-8 lb/ft.
My manual says 20-25 ftlbs...
4 if you have a back seat
The normal size is 15Gal or it could be a 20 gal, mostly it should be the 15gal size