“The electors vote for the person who won on Election Day. If that name is replaced, those during early voting are tossed.”
Electors are chosen by their party as an honor for long service to the party. If Biden is dead, sick or in a nursing home, the Electors he won will vote the way the party tells them. Now some in this unique scenario might well go rogue. Most of them will have little to lose.
“Some, but not all, states have laws requiring Electors to vote for who won their state. However, I believe those laws allow punishment for Electors who are ‘unfaithful’, but do not, in fact change the Electors’ votes.”
It depends upon the state. In some states, if an elector does not vote the way he is pledged to vote, he is immediately disqualified and replaced by an alternate (the slate of electors always has alternates in case of the death or disability of an elector).