My partner is a construction specialist and a broker. 

Cash in the bank is great but your network of lenders, prop managers, brokers, etc is worth so much more.Again congrats!

The times I have seen this have been off-market properties that have not been touched by a broker. 

[Full disclosure - I was the buyer's broker and am the PM for this property...And I'm truly not being defensive or argumentative, simply playing the optimistic devil's advocate (if there is such a thing?]

Make sure your property manager has a licensed real estate broker on their team, make sure they're insured in both general liability and errors & omissions insurance.

Purchase price $634k & appraised value $790k, does anyone know any banks or mortgage broker that can do a refi on this property without seasoning?

My current mortgage broker gave me a 5.75 % rate ?

I'll make a few calls to local mortgage brokers for clarity on these expenses (in addition to what you've added!) 

With current market conditions, it involves putting hundreds of opportunities through the funnel, often through direct to owner marketing or extensive broker relationships.3rd party PM is less about ACTIVE vs PASSIVE than it is about PROFITABLE vs UNPROFITABLE. 

Unless you have the money as well-few do- you need to network with as many investors and brokers interested in those kinds of deals.