How many hours does it take to remove a 3800 engine in a 2000 Grand prix gt?

The fastest way is to disconnect all components from the motor; hoses, wiring, cables. Then separate the steering at the rack unbolt the struts then lower the sub-frame to the floor with the motor and tranny assembled. I usually work on the smaller Grand Am's, Beretta's and Cavaliers. I pulled the subframe as described above from my '95 Monte in 3.5 hrs, it is a w-body and I don't think they changed much from mine to yours. The hard part is lifting the car up high enough to slide the motor out the front. A regular hydraulic shop engine hoist will lift the frame to the ground and the car up but it is slow. The other option is to pull the motor out of the top. At least the 3.8 is easier to access and that would be an option for you. I have 6 LQ1's and it looked easier to go out of the bottom. I actually made a cradle with wheels that I can know bolt to the back mounting holes of the sub frame then use a floor jack on the front to lift and roll the assembly out from under the car. P.S they switched between high and low impedance injectors between 99 and 00 you will need to move your injectors to the new motor.

I have a 2002 pontiac grand prix 3.8 gtp supercharge.what is the best method to use when replacing the flywheel

sense when does a gtp have a flywheel its a flexplate