I stopped by homedepot and the guy said he's not sure (ha? what?)
Do I just use the exterior paint (for outside of the house), or is there some special type for door?
should it be sprayed, brushed, or rolled?
Home Depot clerks aren't exactly the best place to ask a painting question, but hey at least he didn't lie and give you some answer that would have been his best guess. You should use 100 percent acrylic paint, exterior paint for the exterior side and interior paint for the interior side. You can find paints that are rated for both exterior and interior as well. I would use at least a satin sheen so that the door is durable and somewhat washable when you are done. You can spray, brush or roll, whatever your choice. I usually roll them with small mohair rollers or whiizzies. It's too much effort setting up the sprayer for one door IMO.
I went to Sherwin Williams and the guy there said he doesn't know also (ha? what?)
Happen to go to another Homedepot. This time the guy there said should use pray paint bottle like Rust-Oleum. Really? I am quite confused.
can this type be used?
paintguy already answered the question