I do not have any loans through Flagstar Bank, but I would talk to them prior to moving it into the LLC.

It's the concept of buying the debt attached to the mortgage rather than buying the house. 

If I were to approach a seller of a $200k home, and they had a remaining mortgage of $100k, could I get a new bank financed loan for that $100k, and have the seller finance the remaining $100k of equity to me?   

RM (and most other good management software) does double entry accounting, imports bank info, has reconciling functions etc.

So I get that "lag" almost every time, plus I deal with our corporate bank... so they always have that lag. 

Additionally, I have $100,000 in cash in the bank, and my monthly expenses for my home and family are around $3,500.My wife earns between $100,000 and $120,000 from her W2 job, while I've recently lost my job but found a new one that pays $65,000 a year.

Generally speaking, with SFR or small multis, I just rely on the lease/rent roll (and some form of proof of payment; i.e. bank statements, deposit receipts, tax returns, etc.). 

If so, I'd consider those options first as they fit in the infinite banking concept.

Just about any bank can open a joint account. 

Wage garnishment , attach any bank accounts , and or vehicles