The transmissions are the same. The torque converters are different.
No.
A 1999 Dodge Ram transmission does not have an input speed sensor.
No
Yes but the gears have to be changed
No
No. The control solenoid and sensors are not the same.
It is inside the transmission, on the valve body.
You need to put a little more detail in. What engine do you have, and what engine did the 99 have?
If same size, yes.
You add the fluid down the dipstick tube.
Mopar ATF+4