-My theater/rec room is approx 12ft wide by 26feet long. At one end I will have a wall mounted 50" tv. The ceiling in this space will be 6"8, what height should I mount the tv at? taking into consideration that maybe down the road I might put in a riser behind the front row couch.

-Down the road I may purchase a projector with a pulldown screen, probably about 92" wide, question is how far down do these screens usaully hang? I may have to put the front in-wall speakers just below where this screen will hang as I wont have enough width room for the speakers as the A/V rack will take up to much space. As I know the approx size of the screen how far back from the screen should the projector unit be? Thanks.

Mount the TV as high as you can while retaining a comfortable viewing angle. A lot of people mount them much higer than I personally would want to use, but everyone is different.

You could put your speakers to the sides of a 92" screen since there should be enough room. Look at projectorcentral for the throw distances of various projectors.

Once I build the A/V rack which will probably be a min of 24" wide unless I can get away with a skinnier width I wont be able to put the speaker inbetween the rack and the side of the screen.

I think the rule of thumb is to have the midpoint of the screen at eye level. If that's too low, then get as close as you can within reason.

Thanks.

What about the distance from the screen to the projector and how far do these hang down?

Would the speakers be too low if I mounted them just under where the bottom of the pull down screen would be?

It depends on the aspect ratio of the screen. If you're talking about a 1.78 screen, then it's 1.78 inches of width for every inch of height. Therefore a 92" wide screen would be 52" tall.

I'm placing my speakers below my screen because of design constraints, but the best option is always going to be having them behind the screen at ear level. If you went with an acoustically transparent screen, you could pull this off. Your speakers would be lined up with the television, and then would work perfectly right through the larger screen when you pulled it down. If you can't put them behind the screen, at least keep them at a consistant height. If you have to go below the screen, it's not the end of the world.

last question, What about the distance from the screen to the projector? how far should I make the rough-in's from the screen?