I would notify her in person and in writing (big note on her door) including quoting the clause in the lease where she is responsible, and tell her you will be inspecting to insure the heat remains on, high enough to protect your unit, or she will be breaking the terms of her lease and also liable for any damage done in the downstairs unit as well.

I would highly recommend a mentor or even paying a coach to get started.

I have sold in California, took the cash and moved out of state (to Indiana) and highly regretted it - I didn't have a real estate investor mindset then.

Jeffrey:I'm connected to a large group in Indy that focuses on buy & hold SF and apartment (commercial) residential real estate. 

Would real estate prices in certain regions rise rapidly due to demand from both local and international buyers? 

Years ago I spent many months working in Indianapolis and staying at the Canal Street apartments. 

The idea is to convert a multi-family building into condos; but not in the traditional sense where you separate pre-existing apartments into their own condos; but in a way where you combine the common areas of all of the apartments in that whole building, and turn the individual rooms within those apartments into condos themselves; thus transforming the hallways, kitchens, bathrooms, living rooms, dining rooms, porches, balconies into common areas of the condos. 

Inflation itself in the midwest territories will rise over time at a conservative 3% regardless.

Across the street is a big embankment, so no houses or land, but there are several three story apartment buildings on that next street. 

I prefer Section 8 tenants to low income cash paying tenants but there is a damn good reason why many landlords won't put voucher holders in high end properties.