Question about construction contract

[Chase Gu]

Hi, Everyone: I am about to build a small mixed-use new construction. I need someone to review the construction contract with the general contractor for me: either a lawyer or an online legal service provider. Do you have an recommendation? 

I want the contractor to be bonded and insured. What specific bond and insurance do I require the contractor to have for a new construction? 

Also the general contractor wants a 12% fee for any change order beyond the initial scope. Is it reasonable?

Thank you very much!

Qian