是的, $11K cannot resolve the matter

Thank you very much for spending time on this!

(1) Seems like my best option is to hire a lawyer, do it professionally. What would be the cost estimate?

(2) It's correct that even if I give the $11K to the subcontractor, he won't accept it, because he wants the general contractor to remove a claim of ~$5K on his bond as well, and he also wants the general contractor to acknowledge the two checks (of the total 4 checks) he received from the GC are for other projects. But the General contractor refused to do these last two. 

(3) Spending a few thousand $$ is not really a problem for me, but I want this matter to go away sooner and forever.