I agree with the whole swapping the door idea. It would be easier. I have no doubt that you could just swap the parts you need, but you might run into issues getting everything to go into place. If the windows and locks worked in the door when you got it, and you just swapped the door, then you know that it will work once you get power to the places you need it.
If you are crafty with electrical stuff, then you won't have to do anything to the harness.... but you said you were installing an alarm system, so everything should get wired into that anyway. so you're all set to go. good luck with the swap.