re: Need advice on Grilling St Louis style ribs (UPDATE)

The best advice that I can give you, when first starting out, is to just keep it simple. Don't overcomplicate it. You and your family want to enjoy your first rack, and get better each cook after. A messed up rack will discourage you.
A couple bullet points:

Find racks with nice, even thickness on the meat

Pull the membrane

Lightly season all around the rack with a balanced rub. Don't over season the rack, especially the first time.

I like 275 for dry heat, and 250 for wet heat.

Wrapping in foil is a preference thing, and it does produce a slightly different rib than unwrapping.

I don't like using a timed schedule, or an internal temperature as guidelines for gauging doneness. I'd rather go off of feel. I prefer using a bone pulling technique. Meat side down, grab the exposed bones, and pull back and forth, until the doneness that you like. If you feel like you can start to pull them apart, they will be in the neighborhood of being done.

Season or sauce after to taste, and it'll help with developing flavors for your next cook.

Hopefully this helps.