If you do not use a guru, it does take time to recover. Especially on start up. Since I started using my guru, it takes maybe 20 minutes and I am at the temp to start cooking.
You can put several racks of ribs on each rack. I would say at least 4-6 rib racks per rack.
Bubba Keg / Stumps Baby / Super Fast Yellow Thermapen / Lodge Cast Iron Grill / Smoke Vault