Minimum loan amounts are a lender's own policy, not a rule from anywhere above them. Origination costs the same work on a $92k loan as on a $400k loan, and the lender earns less, so many set a floor. A different lender will have a different floor, and the ones that go low are usually community banks and credit unions in your market rather than the big names.
When a small bank keeps the loan on its own books instead of selling it, that's a portfolio loan. Nothing sinister, and it solves the small balance problem, but the terms differ. You'll often see a rate fixed for five to seven years with the balance due or reset at the end, a shorter total term, a higher down payment, and sometimes a recourse guarantee. Get the exact terms in writing and read the balloon date before you get excited about the rate.
On the comp problem, appraisers can go further out and further back in time when local data is thin, and they'll make adjustments for it. What you should expect is a wider range of possible outcomes and a real chance the number lands under contract price. Keep an appraisal contingency.
One thing to check early in a town that size: insurance availability. Some carriers pull back from small rural markets or want a distance-to-fire-station and a hydrant nearby, and a $92k duplex with a $3,800 premium is a different deal than the one you're picturing. Get a quote on the actual address before you spend money on inspections.
