I am in the process of building a strong crew who will build all my projects allowing me to meet my deadline 's and get as accurate as possible on my cost.My financial goal is to make 400k in 12 months An I crazy?

Zestimates have been accurate, but only by accident.

Perhaps I am just lucky, but I have a team member I can trust and more often than not, my pre-determined exit price is the same as what I am given (which gives me confidence that we both did our numbers accurately).

(50k/10k = 5)That has been very accurate on some of my flips but not on some others.

No matter what estimates you use, they will not be 100% accurate.  

They use regional multipliers for whatever area you are in and I can't imagine it to be "accurate" but better than just guessing.

Anything less is gambling not investing.

Would be able to put 25k down on the deal, and taking a 40k loanAssuming 40k, 5 year loan with 4.5% interest it would be ~745$ a month paymentsSo if i assume 40% for management, vacancy, repairs (is this number accurate?)

Zillow does not have totally accurate information and realtor.com is a direct feed from the MLS.As far as the criteria, it is going to depend on your area.  

You can not accurately value a property based on the registry of deeds.