yeah, I wondered about the back end of the TV myself. As I picked up the 27" TV I was gonna use, the one thing I noticed was it's WAY front heavy. If you look at most of these designs, the monitor base is essentially an upside down "T". My plan is to go with a completely enclosed cabinet (look at someone's entertainment center for an example of what I mean) and then wire two exhaust fans above the TV. The reason for the exhaust fans is to wick away the heat. The TV I got for free cuz it was overheating and having problems (also had it happen with a smaller one, too) so I know for CERTAIN you want removal of heat from the back of your TV.
The metal frame seems to be a standard, as they've got the same thing on the machines in the arcade by me. I bet that's just on there so some knucklehead doesn't shove something into it and either electrocute himself or screw up the machine! If you and your fiance plan to have kids, or you may have kids over to the house once in a while, enclose the whole shebang and have one less thing you have to worry about. I've got three 27" TV's. Depths of them from front of tube to back of set are 19 3/4", 20 1/2", and 20". Add perhaps another 2 inches for cords to exit without a 90 degree kink in 'em and that should be enough.....not a monolithic-looking structure, IMO, like a bookcase, but just a bit thicker.
If you want the metal frame, angle iron will probably work just fine. You'll need a drill press and tapping oil to make fastener holes, or be able to weld. Then, just fachion a box frame with that.