A reciever will read the 1.0 channel and direct to the center channel. This is when the direct stereo option comes in handy if you want to spread out to your two mains.

Dual mono is the correct term, as there are two identical mono streams encoded for direct playback over both channels in a stereo setup.

The DTS codec is supposedly much more lossless than previous ones, but I don't know if a standard 768 kbp/s version can hold up against PCM even with the 24 vs. 16 bit difference. The biggest difference will likely be post processing work done on the new mono track. The 30th Anniv. DVD sounded pretty good when cranked up, but noticeably hollow because it had no breathing room with the DD codec. The '91 LD may be a remix, but it has greater presence and depth-especially in the natural bass.