Hi Andrew,
Welcome to the board! Regarding your questions:
1. There may be some teams brining or possibly marinading their ribs but based on my own experience the texture of the meat can get really mushy and the ribs take on more of a ham taste. I prefer not to brine or marinade.
2. Don't over do the rub. I usually give the ribs a light dusting on both sides, let them sit for an hour and then lightly dust both sides again before they go on the smoker.
3. Use of a mop is a personal preference. Some teams do it, others don't. Personally, I don't mop my ribs but I do spritz them with a small amount of white grape or apple juice and some honey if I decide to wrap them in foil for a bit.
The best thing you can do is to experiment and see what you like best. There is alot of great advice and information on this board as well.
Good luck!