OK once again, I did not fasten the 2x2 to the foundation walls. But I did screw them to the ceiling joists. And I'm not against starting over, but my wife will likely not like that idea.
For heating I was going to get some baseboard heaters, and for cooling I figured it was the basement so didn't really need that to much.
For oxygen I have a chimney on one of my side walls, you can see the clean out in the pic. Right above the clean out there was a spot they had an old wood burning stove hooked into it. I spray foamed that, then cut out a 6" hole and put a duct fan in. So I'll be able to switch the fan off and on.
As for the sand box in front. As much as it might help I'll prob not do that, just for the simple reason of height. Don't know if you can see in the pic but that part of the ceiling comes down about 6". So I was planning about 2" between the top of the screen and the ceiling. But then I only have 33 inches from bottom of screen to floor. Plus my center speaker is going in that space.
For space, well if I start over I can change the length and width. Length I can go another 4 feet if needed and width I can go prob around 3 more feet. I figured with the short ceiling hight a 12x20 room was the right size. But then again I don't really know what I doing.
Now budget. Not really sure. I guess around 1000 bucks is what I was hopping for the build part. Lumber, drywall, ext...