I can't address the insulation issue, but many have replaced the thermostat with a digital version. I plan to do that soon. I started carrying a 6 ft stepladder now that we have the HTT with slideout. I always sweep the slide roof before retracting. Nuts or leaves should not harm the seal because it's raised a couple inches from the roof, but a small branch or twigs could mess with the seal. Also the nuts and leaves could roll/move off the top into your living area in travel. We have a long bed F150 for a TV, so carrying the ladder is no big deal.
Enjoy your new camper!
Me, DW and 5 dogs
2004 F-150 Reg Cab,Long bed 4X4
2008 Flagstaff 625D Pup (keeping this one for now)
2010 Jayco EXP 21M Hybrid
ďThis isnít rocket science; itís more like quantum physics.Ē