The military will follow the Constitution. As long as Trump has that on his side then they will be behind him. If he, or anyone else, tries something outside of the Constitution then they will be in opposition.
Yes and the Insurrection act is a totally legal avenue for Trump to follow if he has proof of foreign national in a national election. Or treasonous activity such as an overthrow not our election system. There’s a reason the spec ops got reassigned to DOD Miller.