Here are my guesses:
8. How about Mexicana, via SJO and MEX.
10. There were three airlines that served both MCI and BOS in 1973: TWA has been ruled out, and I think flying DL would require more than two stops. That leaves UA. I'll guess UA's flight was via ORD and CLE, using a 737-222.
I've just purchased a Sep 1972 OAG from legendary aviation historian Imre Quastler. I'm going to have a LOT of fun using it to come up with quiz questions.