Selecting Vice-Presidential Nominees

[True Federalist (진정한 연방 주의자)]

A Vice-Presidential primary concurrent with a Presidential one would be interesting...

IIRC, New Hampshire holds a non-binding Vice-Presidential primary in conjunction with the Presidential primary.

[True Federalist (진정한 연방 주의자)]

I also feel that, in the age of potential catastrophe, the succession list should include a few governors out of DC.

Including governors would be technically possible with a change of the law, but you then have the problem of how do you decide which governor gets first shot at being President.  It also would be difficult to transfer effective control in the sort of emergency that would necessitate it.