I am interested in putting my skill set to work, buying undeveloped land, prepping it for building and then selling.

I agree with all of these professionals when they tell you to go to these meetups (Augusta REIA events, AORE events, etc.).

BRRRR probably has more risks but if you can learn to add vale with a renovation this will be an invaluable skill

Do it yourself if you have skills and are prepared to make a new tool for every county you want to access the data for and, there are no APIs that I am aware of.

Hello, I own a fixer duplex near Mercer in 31201, and struggling to find workers/contractors in Georgia's skilled labor shortage. 

you need a stamp and to become a professional engineer in your state.

Since your combined income exceeds $300K, passive losses from long-term rentals are limited unless either you or your wife qualify as a Real Estate Professional (REPS).

.: *assumes CA averages for valuation, rent, profitability, etThere are strategies for starting small or starting big, that are discussed but I am not entirely sure what would be like too big for a first deal...My inclination is to assume that the larger the asset or more units the better, as there is less tenant risk, professional property manager, etc.

I would say that markets do not go up indefinitely.The Great Financial Crisis and mortgage crisis was one that comes to mind quickly.Not many people saw that coming including myself.I learned how to do short sales during that period as well as foreclosure prevention.It forced me to learn new skills for a down market and like all crisis experiences you learn a lot about yourself and how to problem solve creatively.To Your Success! 

Then focus on finding professional vendors that can clean/repair, as necessary.