If you don't fill the screw hole, make sure you move it more than one diameter to get good wood. Honestly I like them to be slightly tight - it makes a better seal, if you make it loose, you may get more air coming in.
Ditto what Absolute said. If you have to push the door in a little to slide the deadbolt, it will force a tight seal on the door. I wouldn't do anything to it unless it was a pain to get it to slide into the hole.