@Sarah Davis 60% vs 55% of a typical lot is about the size of an efficiency or an adu.

Mini Splits are a great way to heat and cool units that size, however maintenance can be costly with tenants. 

Typically you can get a LOC of 40-50% of your portfolio's size depending on the investments you hold and brokerage.

@Rich Beam I have a couple of laundromats of different sizes.

Since I don't know anything about your stepmom's estate, it's size, her objectives, you can check with an estate attorney about "irrevocable trusts" where you'll be the beneficiary.

A project this size can go over budget very quickly.

If household size is similar for your unit and the tenant's unit, half of the bills should be fine.

I'd say a solid volume of comps, and factor in rate differences, capex upgrades & basic things like inferiority or superiority of the locations assuming price per sq ft, size, etc. are comparable.

Provided a suitable down-size from our old home, with the ability to generate cash flow after we move out in a few years.

The size of the property will impact both budgets.