I guess we will see about the second part. As for the 5th Amendment, I think you are correct, but there are many people out there who disagree, and they have valid points, such as: the 5th Amendment extends to matters of government seizure of life, liberty, and property. In Trump's case, he'd be arguing that this is his liberty being violated by not being allowed to run for President; however, the Constitution doesn't appear to say anything to lead us to believe that running for President is a right insofaras there are many restrictions that extend to who can and cannot be president well beyond the restrictions of who does and does not have protection of basic rights. Furthermore, the loophole in the 5th Amendment that former President GW Bush had tested to its limits stating that one's Constitional rights mean absolutely nothing at all to the government in times of "public danger" could be argued to extend to people who allegedly ran an insurrection trying to capture power once again. I know its sounds ridiculous to apolitical people out of context, but I happen to agree with this one based on all of the ongoing allegations of election interference. The same points apply to the 14th Amendment interpretation as well, since it uses similar language, but there is also the last clause, which would be interesting in this case, since the argument could be made by Trump that the laws as applied here would not be applied equally to some other candidate if the proverbial show was on the other foot. If he has some real scenarios to back that argument up, which I could see how he might, he could win the court case; however, since, again, this is all unprecedented, it's going to ultimately come down to a judge's or judges' interpretation of the law and conjecture about the situation.

Not sure if that matters, necessarily. The president of the USA is chosen by electors, not by popular vote. For example, Trump won the 2016 election by negative 3 million votes. It is hypothetically (for rhetorical purposes) possible that, if one person in each of the ten most populous states voted for the same person, no one else in those states bothered to vote for anyone, and then the same candidate who won those ten states won any state larger than New Mexico, that candidate could win the entire election with a minimum of 11 votes, even if tens of millions of people in the other states voted for the other candidate.