Where do you suggest would be a good place to start on deciding on a location and developing a relationship with a trustworthy property manager and a realtor?

I'm betting it is vinyl - though the house is old enough there could be a linoleum layer under there somewhere.  

Assuming your home only needs basic spit and polish (paint, carpets, a quick landscaping job, etc)  I know some people on this site might bristle at the suggestion but your best bet might be to find a listing agent willing to spend some money up front on those things (to be paid back along with selling commission) in hopes of getting the  home to sell for substantially more.  

Funny thing...when I saw you are from Philly the song from Fresh Prince of Belair came into my head....bet your singing it now too!

My feeling is that if you have a 20-30yr time-frame you are likely taking larger risks/speculating by betting on markets where initial cash flow is high but the market could see both property price depreciation (in real terms) going hand in hand with rents not keeping pace with cost inflation. 

Infrastructure and job centers (such as UMD and a few govt agencies) are reasons I would bet on Hyattsville.

Obviously there are realtors and investors but they are not as "plugged in" with social media platforms like BP so it's kinda hard finding trustworthy genuine people that aren't across the country lol sighhh 

Do you guys know if its a good bet to count on Section 8 for lower-income areas (20-35k real estate)  or better to invest in to 40-60k turnkeys?   

(If betting on them not affording such suit in order to take advantage, one should reconsider his/her life choices.)

If he's a reputable, trustworthy investor, you should have no issues with this.