You weren't paying attention. What did I say about bike sizing? That bike is not a 26" bike, unless you happen to be 7 feet tall. If not, you simply cannot stand over it.

That bike has 26" wheels.

30 years ago Schwinn was a terrific company that made some of the finest bikes in the world. (Don't start Raleigh fans...this isn't the thread for it.) That company no longer exists. The current "Schwinn" is the dessicated remnants of that company which currently belongs to I don't even know who now, after changing hands many many times. That's big box capitalism for you.

It's still probably better than the Wal-Mart bikes, but not by much. It makes me want to sob to see such a fine name reduced to this in the race to produce shareholder payouts.

Brands to trust? (I hate that phrase, but this isn't the place for philosophy either.)

Specialized, Fuji, Trek, Raleigh, Kona, Surly, Burley, Cannondale, Giant, LeMond, Felt, Redline, Haro, Jamis, Marin...that was in no particular order, simply as they came to mind. Some make all kinds of bikes, some are more specific or focused.

Places to shop used?

E-bay. Craigslist. Local classifieds. Garage sales (playing roullette here...). Does your local bike shop (LBS) have a used bike board? Is there a local bike co-op? Is there a used bike store? Maybe a "diamond in the rough" can be found at a pawn shop? (Though I hate supporting the last decade's growth of pawn shops.)

Are mountain bikes cheaper?

In this country yes. Mainly due to the proliferation of "toy" bikes. MTBs are pretty much toys anyway, but the nice ones are much much nicer toys. Road bikes are increasingly rare in the US...pair that scarcity with overall better engineering (lightweight and smooth components), materials (sleek and lightweight yet strong frames), and innovation (STI comes to mind, often called "brifters") and you have a more expensive product. But oh so worth it.