firstmustangrestoration

Ok this may sound weird. I have my 1970 mustang completely torn down to just a shell. All the fenders, hood, trunk lid, doors are all off the car
Here are my questions. I know the doors hood and trunk lid are all fitted to make sure the gaps are correct. Here are my questions. Do they make sure the gaps are correct before paint or after or both?
Next question if it is before and after paint then can I just have the body work done on the shell and have the fender aprons and firewall painted get the car back and do all the suspension, steering and wiring done new engine and trans put in. Then take the car with all the doors, hood, fender and trunk lid for final prep for paint or should I send them all for work at the same time Sorry for the long post but thanks in advance Just need advice on the process Thanks Again