Posted: Wed May 25, 2016 3:34 pm Re: Could i fill a tub with sand for my turtle to roam? Help
About feeding out of water: I've read that turtles need to eat in water because they don't produce saliva that would help them break down the food.
I think the waiting by the door is just standard turtle behavior--they're always trying to explore and see what's out there, and maybe he's decided he knows your room well enough already. You'll probably run into the same problem if you set up a sand enclosure for him too; and you'll need to watch him the whole time to make sure he doesn't escape, flip upside down without being able to right himself, etc.
If you're worried about him being bored, try one of those floating plastic toys that dispenses food (I've found a fish and a ball that you put pellet food in at Petsmart and Petco--the food comes out of holes in the side of the toy when they push it hard enough). And like Steve said, they'll feel more comfortable in a tank that's the right size for them (10 gallons per inch of shell length from top to bottom); mine was excited to explore when he got upgraded to a 40 gallon tank, and then again when I built him an enclosed area to bask above the tank.