2002-1500 to a 2004, yes. 2002-2500/3500 to a 2004, no.
If they are the same body styles, yes.
It is stored under the front passenger seat
No, they are not interchangeable.
Parts from a 2002 Dodge Ram will not fit on a 2008 Dodge Ram. The parts will not fit because of the years in between them.
No, they have different tone wheels for the cam and crank sensors. The engine would bolt in, but it will not run.
A 2002 and before Dodge Ram 2500.A 2002 and before Dodge Ram 2500.
No, mounting brackets on the door are different. (I made the same assumption, I purchased 1999 mirrors to install on an 2003).
yes
The factory alarm is reset with the remote or by unlocking the door with the key.
The 2002 1500 parts do not interchange with a 2000.
Yes
A 2002 Ram does not have EGR.