I really liked the "hard science" - the bit about the sidereal time was very interesting. The parts about finding or describing each universe made a lot of sense, too - there are a whole lot of alt-worlds out there, and Herb would need some sort of way to keep them organized.
As a non-techie, I do appreciate the hard science stuff. I tend to do a lot of technobabble and handwaving in my fics.
Lois's delayed aging makes total sense the way you describe it, as do their reasons for creating new identities. I personally feel that they might go off and work at another newspaper for awhile, or at least the Daily Planet branch in a different city, though. If "Clark Kent and Lois Lane" get old and retire, and a new "CK and LL" come on board, it would be very hard to maintain the fiction that the two sets of people are *different* sets of people. Geographic distance might be the best disguise here.
I always hoped that Lois would live a good long time, though. Yay for explaining how she will.
