For both the applicant(s) and a co-signer, you want to understand their habits...financial, employment, legal, character, etc., as Bad habits in one area typically carry over to other areas, and will land you a poor Tenant (or co-signer) choice.

Work with a CPA to optimize your tax returns to reflect sufficient income for future loan approvals.

The good thing about househacking a legal multifamily unit is that lender allows you to use the vacated units of 75% market rent as an income to offset the potential current mortgage.

Generally there is consensus that DSCR Lenders can only offer a 1% prepayment penalty for up to 3 years in MI, but some lenders have recently reportedly been flaunting this rule - I would just tread carefully here in this area, generally not advisable to get potentially tangled up in a flawed legal doc with a non-sophisticated or fly by night lender

Regarding number one, while it may or may not be legally necessary (not sure), I think it's a good idea to have a separate account for each entity.

If you didn’t specifically advise on what to do, they drew it a specific way at the end of the day you approve the drawings to be built so it’s not their fault it appears and they should be compensated for the revisionIf it’s something they screwed up (does not appear to be case here) - then they correct their error

Taking legal action against another party necessarily involves questions of law and can result detrimental legal impacts on him if he files a lawsuit without proper grounds to do so, or where the opposing party may have counter-claims against him.

With my w2 job, the agreement we sign to work outside the office specifies that we will work at a designated specific approved location (our home).

If the issue continues, consider offering a formal payment plan or seeking legal advice.

It makes ADUs under 900 sq. ft. in SF zones legal BY RIGHT, statewide, starting in February.