Be sure the builder has experience and a track record, and check references.

Take a list and send half one letter and half a different one then track your results.

But I am receiving about 3-6 calls a day on the yard sign, and usually at least one of those is interested after hearing the automated voicemail with the details.So my question is this, how do I keep track of the interested prospects as they call?

I'm all about buy and hold, so yes, I think you're on the right track for sure!

I keep track of the reserves to know that the money is there when needed. 

(By the way, I recommend using Podio to keep track of all this.

Life is much easier when you have a good track record of making money and paying your bills

Probate filings are public record, so you can usually track down related property through the tax record and contact the parties involved, preferably family members instead of attorneys.  

Sounds like you are on the right track.  

"Evaluations" are not a metric that I track.