“If I have any interest in this property I am signing them over to you”..... along with any liens, debts, problems and I’m not guaranteeing you anything.

I'm often not quite sure what exactly is meant, because they have pre-determined codes that might not fit exactly the situation.

I am using private money and am trying to determine is this a good deal.

Is a signed contract through a RE lawyer enough to protect our interest if we did it?

.$4850 sounds about right...yeah, the amount is pretty much determined by the city...so just pay them so that you get your permit as soon as you can.

Will they take less depends on if they have determined that the house is worth less than the FJ, and they decide to take less now, instead of later......otherwise they will bid up the FJ amount.

Here's a blog article that covers many of those sites that may be helpful to you: How to Determine Fair Market Rent.

I am trying to determine if the purchase of this house is a good deal for tear down and new duplex construction  numbers are 105k for house $225k for renovations.

Did you sign an exclusive agreement with them? 

Although, we have a general contract for any work, neither of us signs it - I pay him as the work progresses.