On portability, ask the lender to explain exactly what they mean in writing rather than relying on the label. Does it apply to another property, depend on fresh approval, or simply not exist for this product? The same goes for early repayment: check whether extra principal payments, a full...
The practical answer seems to be a written walk-away test rather than a market prediction: maximum total cost, minimum cash reserve afterward, required building features, and a holding period long enough that an immediate resale is unnecessary. Then verify those limits against recent closed...