You are thinking of Section 3 of the 14th amendment. Voters are attempting to use it to prevent Madison Cawthorne and Marjorie Taylor Greene from running. No luck so far. If anyone tried to invoke this to prevent Trump from running he and all of his followers would label it another witch hunt. And if it went to the Supreme Court, Mitch McConnell packed the SCOTUS in Trunp's favor.

Trump's legal fees are being paid for by the RNC. I wrote about it here: https://medium.com/politically-speaking/the-republican-party-is-paying-trumps-legal-bills-96328de08e1.