I've done all mine in Excel and even my tax returns. 

Both Rogers Park and West Ridge will be great long term stable options but the Northside of Chicago has really become more of a appreciation market over cashflow just because of the limited supply of properties and the aggressive property tax increases occurring due to the Assessor revaluing northside properties.

How do you ensure you're being paid and everything is legitimate?

I am a new investor in the Austin area, with property tax and interest rates.

If she is going to live out her days there, it is "tax wise" better for you to inherit the property than for her to change ownership to you while living (it's a thing called a "stepped up basis" (look it up).

If you turn it in to a rental you’re giving up the tax free gain.

IRS taxes 2 years, w-2 right now because we are before 2023 return due 3 years, paystubs 30 days, mortgage bills, fire insurance and HOA bills, bank statements past 60 days.

I've been part of deals where the investor was in and our of an out of state investment in 90 days and netted 45k after taxes. 

You are mixing up two different things.You will probably form an LLC that will own the property.You will then have to decide ownership percentages, who managing partner will be and who will do what.For tax purposes, you will need to decide on corporate type: C-Corp (no), S-Corp (maybe), partnership (1065 tax form). 

A Tribute to Julio Gonzalez @EngineeredTaxDear BiggerPockets Community,As we traverse the intricate landscape of real estate investment, it is imperative to delve into the profound significance of proof of income, specifically the last two years of income tax returns, as mandated by lenders.