I plan on building a 300 sq ft studio in my backyard and either rent it out long term or maybe do Airbnb.

I am always doing something involving not only real estate but personal development from using my vehicle as a class room for Jim Rohn, Napolean Hill, Brian Tracy, Les Brown you tube videos (just to name a few) or audio books I've dowloaded somewhere.

In your down time of studying like crazy for your real estate license take the time to listen to the audio book millionaire --you can always buy it but I'm sure your eyes will be googly eyes after so much reading and rereading of license laws and statute-- real estate investor it's on YouTube for $FREE.99

The 1 studio apt was set up sort of like a hotel room.

It depends on the property, location, and volume - we mainly focus on small studios and 1bds.

It is a 500 square foot studio in a co-op selling for $145k.

Not really a duplex or triplex, but a house that has potential to rent the basement studio space. 

Rents are around $800 studio, $1100 1 br, 12-1400 2 br and more for 3 bed.

I'm about an hour and a half away from Coatesville so I'm not intimately familiar with the area, but last year my best friend was living in a triplex there and he was paying $1,000/mo for a studio apartment.

Consume everything you can (books, audios, meetups, etc.) on investing, and just realize this is a time to learn, not a time to invest.