well, i've been painting my interior, and it looks tight. however, when i leave it to dry, and come back, the parts have a rough feel to them. so, after letting them dry for about one whole day, i went and wet sanded one of the parts from the door. i used 1000 grit. it stripped a little bit of the paint though. nothing drastic, and you can only notice a little in not so obvious places. did i use too rough a grit? should i use 1500 grit, or just let the pieces dry some more and then wet sand them. fyi, i cleaned the surfaces REALLY good before i started to paint, with sem stuff: sem soap, plastic prep, vinyl prep, sand-free.

use 600-800 grit. it will still leave the factory grooves in the panels.

also after you sand it, make sure you wipe off the dust before putting another coat on it

so sand with 600 grit (which i also purchased) and do one more coat? wet sand, or dry sand. anything i should do post-final coat?

wet or dry, doesnt really matter. go ahead and wet sand it. just clean it good before the final coat goes on

...but should i do anything after the final coat? will/should it come out smooth after that final coat? i won't have to sand again? it won't feel rough again?

Sand down the rough areas then wipe off the dust, let dry then spray another coat, after it has dried a bit (give it about 30 min) use a wet sponge to wipe off any overspray or paint dust.

>after it has dried a bit (give it about 30 min)

it would still be wet somewhat though, right? pass the wet sponge even though the paint's not completely dry?

drying time depends on what kind of paint you are using