Comps are alot different than back yard grillers/smokers, imho.
We like it when you bite the rib you can see your teeth marks and the meat pulls clean of the bone. Nothing wrong with it pull'n all the meat off in one or two bites. What ever floats your boat, Rock.
Really watch them when they are in the foil, that is where things can go bad fast due to the steam. When in doubt, take them out of the foil. Save the juice as a "mop", I pour it on later.
To know when they are done is by eye. Get gloves or tongs and do a bend test to see if the meat is pull'n away and the ribs act like they will just almost fall apart. It really does take practice, and if you can get us some pic's we'll do our best to help any way we can.(not really, I just want pix!
Good luck, Rock, you'll do fine.