All "transit corridors" are meant to be some sort of rapid rail, up to 125 mph, with the exception of the purple line, which is supposed be a standard "trolley" (LRT) line.

No technology selection has been made for any of the corridors, as all of this is still at the crayons-on-a-map stage.

My best guess is that, if any of this actually gets built, that for the most part it will be done using standard gauge electrified rail, mostly with Caltrain-like EMUs.

No new airport would be needed, the idea is to make TIJ effectively an extension of SAN thanks to the "transit corridor" connecting the new "Grand Central Station" (I hate the overuse of the term "Grand Central Station", it's become such a cliche) with TIJ via the Cross-Border Xpress.

IMO, the Coronado connection would have to be a tunnel, since it is too close to two airports (SAN and North Island) for a bridge tall enough to accommodate aircraft carriers? And it would be expensive.