Good questions. The actual footprint is about 75% of what you're seeing. There's about 3-4' on both sides of the tent that extends out, much like a vestibule on a ground tent. As it is, the tent will comfortably sleep 3 adults or a car full of kids. I also chose to set it up in this configuration, rather than having it out over the hood, because I didn't want to inhibit my ability to open the rear cargo area by having the tent protrude above the rear hatch. The nice thing about this setup is it allows for access to the tent from either side of the vehicle with the overhang providing a small area (much smaller than a full awning) to provide some shade.
As for comfort, the mattress is extremely comfortable and soft with the shell of the mattress easily removable by zipper for washing after a couple days of camping and getting sweaty, etc. Also, and most importantly, the fabric is "aluminized" polyester which makes it 100% waterproof but also extremely breathable. The aluminum reflects the sun's rays so it helps keep the interior a bit cooler than other RTTs I've used that are poly-cotton.
