He is just adorable! You sure did hit the jackpot with Benji. His coloring is beautiful.
My suggestion would be to have the vet check him for a chip today when you go. If he is not chipped you can have that done along with the neuter.

As for his shots many states charge more when a dog is not neutered so it might be best to wait until his surgery and have it done then. I know in IL it is triple the amount for unaltered dogs. He can always wait to be groomed for a few weeks if you give him a nice bath and brush/comb him.
That is so odd that the woman hasn't cashed your check..........actually it is odd that she even accepted a check from a CL ad.