As other states have done previously for unqualified presidential candidates.
Yep. This isn't even a close call. It's well settled law that states control their own ballot access, not the feds. The states couldn't impose additional requirements for presidential eligibility, but they're certainly entitled to verify Constitutionally mandated eligibility criteria.
The electors appear on the ballot in North Dakota, along with the notification that they are committed to voting for Caligula, Nero, etc.
Yep if they don’t qualify on the ballot they can’t recieve electorals votes either and can not be counted if someone fills in the name. Only qualified candidates can be counted as fill ins.
I would think the Secretary of State can require whatever documentation he thinks appropriate or the legislature specifies in the state election laws.
You may be correct, but it was not always so. I remember voting for Gerald Ford's electors, using an old fashioned, put an "X" in the box, paper ballot, in a volunteer fire department's station. That ballot had the names of those electors. But of course it is a small state and only had 4 or 5 electoral votes (has 5 now).