Try this explanation on for size...
OK, what if Weaver isn't the ghost town...
Oh, yeah, it's filled with the mutated descendents of the bomb survivors, but it's not a GHOST town.
The town with the diner is the ghost town. The mutants kill people and they become ghosts who go inhabit the ghost town and try to keep people from going to Weaver.
As for the blackbird...I dunno...maybe a mutated super-intelligent bird?
Just a guess.
Minor quibble: The neutron bomb was not invented in 1948. It was invented in the '70s.