I cut my racks into rib pairs - two bones per piece. This gives more surface area for more even cooking and more smoke flavor. Typically 5 hour cook for baby backs. Ribs on at 212, let temperature come up to 225-230, then hold. Visual check at 4:30, light application of sauce on half of them, and let the temperature come up for the last 30 minutes.
I do not wrap, ever.
On the Weber, I use a mix of whatever briquettes I have (usually Cowboy or something similar) and Rockwood lump.
I lightly salt the ribs 6-12 hours prior to cooking (the night before). I make my own rubs. I do not put any sugar in my rubs, ever.
Straight water in the SnS when I cook on the Weber, a cheap beer in the diffuser when I cook in the Keg.
I don't check meat temperature with ribs. I do it by how much they've pulled back from the bone.
Be careful with lower temperatures. You really need to be up above 220 for the magic to happen.
I don't leave any meat out to, "come to room temperature", especially when cooking low & slow. I want it in the smoke for as long as possible.
A Tip Top Temp is your friend when it comes to maintaining temperature. I can leave on a motorcycle ride with my grill(s) going and not worry about the temperature going too high or too low.
Best of luck.