There are some amazing physician loans available that can allow you to purchase a owner occupied single family property with 0% down. 

Working on an owner finance deal and I'm curious what technology you use to keep track of payments and amortization schedules.  

I  Income:  The amount of property you can buy will be dependent on your Debt to Income ratio.  

A high property tax rate will increase the taxes more quickly as a percentage of total expenses when the property value increases.

So the property owner can never sell?

In the event that a seller was to owner finance a property to a buyer without a SSN, is there a market for the Note to be sold to a note buyer?  

If you really hustle and are smarter than the average bear, you may make enough money that you can buy an investment property.

STR Property management is common and I know a lot of folks doing this.  

I would also add that you join your local REIA chapter (Real Estate Investor Association) as it will allow you to network with other STR owners and get more location-specific information. 

Since part of your property is a rental, I believe a portion of your mortgage interest should be a tax deduction unlike your other debt.