Specifically, where are the opportunities and how do you spot them? 

Most of the bad noise right now is about downtown skyscrapers and REIT or Syndication apartment complexes where they played short term versus long term interest rates wrong.  

A good mix of LTR'S is a very good idea so that all your eggs aren't in the STR basket.I like tourist destinations where STR'S are heavily ingrained and almost impossible to ban or regulate out of existence.

You may be better served with a market where you would have more purchase options and more margin (equates to less risk).I like San Diego RE.

It's near where I live though.

On the flip side, if you've got a bunch of Section 8 tenants living in a building that's in a neighborhood where a lot of the tenant base has good jobs, high credit scores, and are generally reliable people, you've got the most risky tenants in that tenant base and that ain't what ya want.

A good deal is one where the rent covers most or all of your expenses.

The interest calculations is where I'm having some difficulty.

One thing though is that there are requirements coming into effect soon where wholesalers will need to get their license in PA for any properties that they wholesale, so you might want to look into that before it becomes official!  

Where you would put in the mortgage the seller is financing.