They would be putting in some money and their service as sweat equity, and we would be putting up money and my wife’s services. 

If you have no idea what is going on with this capital call, then the bias should be "no" until you understand what is going on and believe that is the best possible use of your hard earned cash.

Due to the confusion on their end and their slow response, it's costing me more money than if I just went directly with the vendor from the start.

Good people gave me work, I learned more skill, more money, worked hard!

They are looking for "who is making how much money under what circumstances".

Maybe I'm no longer a low risk bond investor, maybe I'm parking my money in $VOO instead, CRE REITs, or perhaps higher risk higher return bonds. 

They saved up money.

Getting something under contract is as easy as give the seller all the money.

It is a complimentary strategy to pull some of your money back out and hedge your bet.

The lender may figure if the borrower had this kind of money they’d be making the mortgage payments.