You can leave the interior in except for the parts that cover the jams like the door sills and you'll probably want to remove the door panels.You could leave the door latches and mask them off. You'll want to remove the seals around the hatch and the taillights, side moldings and side markers, and the grills in between nose panel and front bumper. It might be a good idea to remove the hatch or else you'll have to mask off the massive opening it creates leaving it open to paint it all the crevasses. You'll want to remove the gas door and mask all the plastic off inside and remove the latches. You'll probably want to remove the door handles as well and paint them separate too as there is a rubber gasket around it and the key hole. You'll probably want to take the moldings off from around all the windows and windshield/hatch and take the wing off and paint it separate.
As for the engine bay..You'll pretty much have to remove the engine and most of the stuff in the engine bay if you want it to match as well as the cover under the hood. Usually you just take the hood off and paint it separate.
The hood, door handles, wing, gas door and maybe the mirrors can he painted at the same time. If you have a targa, you'll want to remove it and paint it at the same time as this other stuff as well. Tape lines are ugly and getting overspray on seals/moldings is just as ugly. It'd probably be a good idea to remove the headlight panels and paint them with this stuff too and mask off the whole area as you don't want over spray on the lights.
I probably forgot some other things but you get the idea.
When I painted my car, I removed the bumpers as well and painted them separate because I didn't want overspray on everything behind it(intercooler,oil cooler, etc..) and the muffler and gas tank in the rear. The wheels will be covered but if you don't remove the inner fender plastics, there will be overspray on them as well..Black might not show up that easy but still..you get the idea.
