1.) It doesn't have to come from a campaign account for it to be illegal. It just has to be "any gift, subscription, loan, advance, or deposit of money or anything of value made by any person for the purpose of influencing any election for Federal office" that is over $2,000 and/or is not reported. Trump's reimbursement to Cohen breaks this in both regards.
2.) Trump falsified his Financial Disclosure Form when he took office and failed to report that he owed Michael Cohen $130,000.