BP is maybe the greatest free resource to help you get started in Real Estate Investment there is on the internet.

These are both helpful because as an investor I can see how much I am returning (on a cash flow basis) against my initial investment and allows me to compare determine if my current equity position is allowing me to maximize my returns or if the equity would be better off used elsewhere.

I’d be curious to hear from actual appraisers on this, however as a solar professional in my experience appraisers will not immediately ad value for solar, despite the appraisal institute determining through a comprehensive study that solar ads $20,000 value for every $1,000 in annual energy savings.

Sometimes more, sometimes less with a lot of factors going into this determination (credit score, income, address of property etc.).

Using the local market comps can help you determine the market value of a house to ensure that you're not paying over market value for the home. 

There are several military real estate investor communities around the internet.

In my experience they are essentially the same: Crowdfunding deals are basically syndications but done over the Internet. 

The Purchase Price matters as that is what will determine your Cap Rate, Total ROI, and Cash-On-Cash ROI.

How can I determine if a market is too saturated to start investing?

The forum is full of posts about finding buyer's real estate agents and how to determine that they are good at working with investors.