It's not a requirement. It's a political strategy. If the candidate is from a "liberal elite" coastal state, then the running mate has to be from flyover country. It's pandering.

John lives in Jersey, actually.

They could be from the same state but picking a VP candidate from another part of the country is seen as one way to balance a ticket. They could pick someone from a swing state in the hopes it would help win that state, or try to balance out the ticket on the political spectrum by picking someone further left or right than the presidential candidate. In 2008 the Democrats balanced out the young black candidate with an old conservative white VP candidate, so there are other ways to balance a ticket.

That's not a requirement, it's more a tradition because the "electoral math" is better.

They can both be from the same state and electors from all the other states except their own can vote for both of them if they win that state (Potus and VP are actually voted on as separate votes). BUT electors from their own state could only cast their votes for one of them!

Per the 12th Amendment:

The Electors shall meet in their respective states and vote by ballot for President and Vice-President, one of whom, at least, shall not be an inhabitant of the same state with themselves

Just another stupid thing about the Electoral College system. Say for example Newsom ran for POTUS and his VP pick was also from California. California electors could only cast their votes for one of them (obviously they'd choose to apply them to the POTUS seat. So the VP might lose to the VP of other party! So stupid. When Bush picked Cheney, Cheney was a resident of Texas and moved to Wyoming so Texas electors would be able cast their votes for him.