@Marty Summers It depends on the size of your 401k, but investing in real estate directly through you 401k is kind of a pain because you are investing with tax deference but that's one of the reasons to invest in real estate because of all the writeoffs. 

Read some books and attend podcasts so you learn how to underwrite and size-up deals that will make you money.

I can be personally debt free and have my budget covered on one right size deal.   

This means that buy & hold is my best bet.  

Your 65K house may be a problem for a portfolio lender because of the loan size, but with write off's you may be able to use your tax returns to get cash out for that one. 

That's your best bet for stability, rent growth and appreciation.

If the appraisal comes in lower than the purchase price, a lender can decline to approve the borrower unless a change is made to the purchase price or the size of the downpayment.homeowners’ insurance is purchased (or substantiated, if the property being purchased includes homeowners’ insurance as part of association fees or similar arrangements), and proof of homeowners’ insurance is submitted to the lender.

You bet! 

I bet the $100k condo is in a rough D area, bad neighborhood with bad tenants.  

With that size property, you'll have staff to run it so you're not involved in the day by day.