I have been following this story closely and feel I know quite a bit on the topic, so here goes:
1) From what I gather, the U.S. Coast Guard does not allow at-sea transfers of passengers unless they abandoned ship, which wasn't necessary. Also, given the waves and wind, there would be no safe way to transfer passengers to another ship as a gangway would be too unstable.
2) There are backup generators, but they were built and placed for an 'emergency'. Basically, this generator is located away from the engine room, typically in the funnel housing but it's purpose is to supply power only to systems deemed 'essential' in an emergency situation such as communication and navigation equipment, lifeboat davits and select lighting (including at floor level) throughout the vessel. In essence, this system was designed to be used on a sinking ship, not one that's 'dead' in the water for days, hence why sewage and water systems aren't hooked up.
Going forward, I would imagine all newbuilds will have their diesel generators located somewhere outside the main engine compartment to keep this from happening again. I dunno how the cruise lines could retrofit their current ships though.
Ultimately, the Triumph got back 40% of its power a couple of days ago and they have power to the MDR and several elevators although half the toilets are still out. In all honesty, given the information readily available, the passengers aboard Triumph have more going for them than those aboard Splendor did a few years ago. The media is eating it up too.