The exemption story you heard is partly real and stated far too broadly. Many states treat business-purpose loans to an entity secured by non-owner-occupied property differently from consumer mortgage lending, and some have exemptions based on how few loans you make in a year, but the rules and the triggers differ state by state and a few states license private lending activity regardless of who the borrower is. That question has to go to an attorney licensed where the property sits, and it's a cheap hour compared to the alternative.
On costs, a first set of documents drawn properly, meaning the note plus the security instrument and whatever subordination or consent the senior lender requires, commonly runs somewhere around $1,000 to $2,500 with an attorney. Recording fees and any mortgage or transfer-related tax vary widely by state, from under a hundred dollars to a meaningful percentage. A lender's title policy or at least a title update is a few hundred and up. If you outsource collection, third party note servicers typically charge in the range of $20 to $40 per loan per month, sometimes with a setup fee, and that also gets you payment records and year-end statements you'd otherwise keep yourself. Confirm every one of those in writing before you agree to a rate.
Insurance: ask to be named as mortgagee or loss payee on the builder's risk and hazard policy, and get the certificate before funding, not after.
$55k is an ordinary gap size. Gap pieces are usually $25k to $150k because that's how big the hole is. The thing worth sitting with is that $60k is your whole position in one deal behind someone else's loan, and a junior position can go to zero in a deal where the senior lender still gets paid in full.
