As such the skills, expertise, experience needed to succeed are FAR GREATER than what’s required to be a successful passive real property investor.  

The city isn't calling their areas C and D areas, it's a made-up system that takes into account random data points and personal preference and "skill."

To make as much money as possible, eliminate all stresses, outsource until you learn the skills yourself, etc.Which is most important: cost or quality? 

The good/skilled contractors like to work in better areas and they can easily do so.

What skill sets can you add that help keep you motivated and moving forward?

I have average skills negotiating rehab prices.

I am looking for any advice on how to prepare for such a career as a teenager; whether it be books to read, articles, ways to get more experience, or tips on skills and habits to develop.

Brian, Dmitriy, and Jim Hitt from American IRA all have the skills and knowledge to you help you.

I've applied to many part-time accounting-related positions for experience as I transition to graduate school in the Fall, but cannot get hired because I don't have experience.With all of this being said, I have no clue to whether the path I am choosing (tax) is going to give me the best opportunity for real estate or if I'm wasting my time/resources on skills I might not use as much when I actually reach my goal to be an investor.

Since you are just coming out of the gate into REI,I would recommend taking a stab at wholesaling first.It will help you develop and fine tune your investing skills with less risk.