To answer your questions:
1.) Yes, you can take off the homo door trim.
2.) With that, is it hard to do? Well...its only held on there with double sided sticky tape...how strong are you?
3.) What you will need is some heat to relax the double sided tape, such as a heat gun, you will need either a specificity trim cutter/remover, or you can use some fishing string to cut it, though there is two little aligning pins that poke from the trim into an aligning hole on the car to center and level them, so its kinda not fun to work around those.
4.) I see one disadvantage by not having them...door dings from other ass hole drivers who park next to you and cant watch their doors. Not worth the rick to remove them if you ask me. Also, once removed, you will have several holes in the doors and body of the car that have to be filled, and painted over to have a totally shaved look. Its not a matter of removing them and your done, you will have some welding, body work, and repainting to do after they are removed.
~F~