Rent payments from the medical LLC are fully deductible as a business expense, while the property-owning LLC will report the rent as taxable income, which can be offset by deductions for expenses like mortgage interest, property taxes, maintenance, and depreciation.To ensure compliance, document how FMV was determined—using market comparisons, an appraisal, or similar data—and draft a formal lease agreement outlining the terms, rent amount, and responsibilities.

The mortgage payment is $1,000 on each house, so you earn $500 per house or $2,000 monthly.

Together, we have over $200K (mostly in stock market investments), and our parents may help with the down payment.

Based on what my real estate agent thinks that this quote will be, roughly, and the after repair value, it looks like I could buy this property in cash, spend a month or two fixing the damage, and then put a mortgage for roughly 1.6x what I paid for it and thus have a cash flowing property at a few hundred dollars per month and a little more money in my bank account ready for a down payment on the next deal.

I even bought 3 properties in one day using the HELOC to fund the down payment on each of those purchases. 

You can often get better rates with a national lender, but the customer service is non-existent, communication probably sucks, they may ask for the same documents multiple times, etc.

If they are up for renewal and you elect to non renew them you must stop accepting funds from the occupants after the lease expires (accepting rent after the lease expires may make it appear you have a tenancy at will agreement). 

But as far monthly payment you could easily buy a house in a cheaper location have less roommates and the same monthly payment or the same number of roommates and a lower monthly payment.

Ignore the $1,250 per month because that's your cost of housing, if you didn't pay that on the home you'd have paid that in rent so that's a non factor. 

With your income, you may qualify for an FHA loan with a smaller down payment, but buying now could limit your borrowing power and increase monthly payments.