I'd like to get into real estate small time REI to supplement my full time work. 

These should not be your primary funds for rental property emergencies, but they may be supplemental in extreme situations.I would say for one property, keep around $10,000 minimum in reserves.

My objective to to develop a portfolio of multi-family units that will supplement me in retirement (within 3 - 5 years) so Cash over Cash return is key for me. 

The owner reports profits, losses, and deductions on Schedule E, Supplemental Income and Loss, like an individual rental property owner along with IRS Form 1040.

I think another option is to see if I can get a physician investment loan to buy a duplex or multiplex in an area like Indianapolis where my family already has some real estate so that it can generate enough cash flow after mortgage, property tax etc to help supplement my rent for residency. 

Do you need to cashflow quickly to get out of a W2 job, are you looking for long term equity to supplement retirement?

At -5° if will still put out the heat that it is supposed to, but efficiency will fall.You may need supplemental dehumidification and if you have a tight enclosure you might need supplemental ventilation.Anything you can do to tighten and insulate the building will help ensure that this project is successful.The proper way to size a mini split is to use a Manual J calculation and to use results from a blower door test as an input for air infiltration.

Somewhat a modified BRRRR supplemented also by my 9-5 career.

Many are just trying to be as quick as possible, while navigating the regulatory and supplemental requirements, in order to keep their license.

This will be a side job, and therefore source of supplemental income.3.