When he sells he doesn't finance 100% of the purchase.

It's doesn't really sound like you are much into being landlords so doing a 1031 might just change from "annoying when things come up" to full fledged head aches when you buy more and or larger properties in your current market.

In exchange, he gave her a small rent discount and even helped her relocate some of the larger items.

Why do you think purchase contracts are so long and have such small print?

For example because New York is a generally more expenisve market, you have larger loan buy downs, bigger dollar appreciation, etc.

Larger cities offer better infrastructure, such as international airports, interstate highways, and a broader talent pool, making them attractive to businesses and tenants.Avoid Rent ControlRent control laws can hinder your ability to adjust rents to match inflation, limit tenant screening, and complicate evictions.

After several calls with some of the larger PMS providers, where I really took the time to dive into their products and compare features, pricing, and more, we've decided to go with Hostfully.

Part of a larger development. 

We are considering building a small multifamily a couple duplexs, a tri or quad in a small suburb of a larger city (ie Nashville, Knoxville, Atlanta, Ashville). 

(The difference in rate depends on the deal structure, e.g., the ratio of rehab dollars to purchase price.)Like a HELOC, you only pay interest each month on the loan.