If you are exceptionally strong borrower they will work with >20% down. 

For me, I would want a strong start in building a portfolio with no credit card (or auto) debt and adequate reserves for the future property in the event things go bad.  

As suggested the solution is to send him notice to not contact you directly in the future, block all communication,  and I would strongly advise that you tell him that you will release him from his lease and, if your state codes allow it, you will not be renewing his lease. 

Attempt to transition to a new job as quickly as possible though possibly having to dip into my Roth IRA, but hopefully still having the option of taking out a mortgage once I secure a new job being that my credit score and other factors are strong. 

I buy for cash flow first in markets that are strong and growing.  

The bugs have had 107 years to munch away.I strongly suggest that you include a home inspection contingency in your offer to purchase.I don't know how sharp these sellers are, but I also strongly suggest that you have either a good real estate attorney or a Realtor represent you in negotiations. 

Aside from understanding how to build the buildings and how much they cost, you'll need to know how to understand how to analyze deals at a higher level to see if they make sense - what are the rents/sales you expect to achieve, what are your financing costs, what's the timeline....I would strongly suggest taking real estate and/or corporate finance classes as well - preferably as a minor if you're able to.  

If your current agent can't do this, I strongly suggest finding someone who can.  

If a buyer wants attend the entire inspection that's fine but the strong majority of buyers prefer showing up at the end. 

Many investors utilize different strategies in different markets and different times in the market cycle, but it’s good to nail down one key skill at a time and get strong at it.