I installed 6.5 inch 3 ways into my '94 Accord myself. The hardes part of removing the door panel is the door release itself. The rest is simplistic. The reccessed screw in the door pull is indeed the only screw that actually holds the door on the rest of the panel is held by the standard push into the door type plastic pieces (whatever they are called it escapes me at the moment.) The door release is the only issue being that it must be carefully removed but it is not a huge issue in and of itself.
As far as the deeper then the door can handle speakers there is plenty of room on the door paneyou will need to replace them if you want a better systl foor them so if you make mounts (A drill a jigsaw, some plywood and pressboard, gule and lastly clamps and you can make your own mounts easily.)

The stock stereo sounds a whole lot better when you just change out the speakers and you have to replace them if you want to upgrade the stock stereo system anyway.