No! No you can't. The transmissions are entirely different and would not bolt up directly. Unless of course you did some major fabbing to swap the powertrain out of the 95 into the 68, but why would you want to do that?
Yes.
Should be a plug on the side of transmission
Yes
about 1,200 to 1,300 RPM.
it takes 5 quarts of mercron decron111
The speed sensor is in the engine compartment on a 1995 Nissan Sentra GXE automatic transmission. It is on the back of the transmission.
Yes
6-speed or 4-speed auto
You use gear oil in the standard tranny. According to the 1995 Chevy Camaro Owner's Manual Page 7-50 Part D: Recommended Fluids and Lubricants. Manual Transmissions take "DEXRON -III Automatic Transmission Fluid" http://www.f-bodyhideout.com/techman/1995camaro.pdf
Check
If a transmission speed sensor fails, the transmission will default to second gear.
Should be a 4 speed.