can the engine and transmission be removed together in one piece? also the engine has not been running since 2000, what is the best procedure to prepare for trying to start it?

Yes they can. Some say its the best way. Things to check are enough ceiling clearance to get the whole unit out. Also the lift has to have a tilt mechanism on it. One more thing, how are you going to get the units apart once out? Think ahead on the space and equipment available.

Have fun.

I agree with Vince that removal as a unit is preferred if possible. Not only will you have to have adequate space overhead, the entire vehicle must be raised sufficiently to allow the transmission to swing down enough to get the engine and oil pan sump to clear the radiator support at the front. Usually, the rear of the vehicle will be best raised somewhat higher than the front as well. Be sure to use adequate support under the rear axle housing AND the front suspension because you will have to remove the transmission crossmember from below and if it fell on you, that would put a real damper on your day. In re. to starting an engine that has sat for a while, you really don't provide enough information to cover all possibilities. If it has been left out in the elements, it may not be able to start at all without complete teardown. On the other extreme, it may just need fresh fluids and be ready to fire off.