B-2 visa & public school enrollment

My sister's 6 years old boy will be in bay ara in Sept. He had got B-2 visa in China.

Can he be enrolled to public school?

He will need birth certificate, medical record, residence proof, a document showing I am his guardian, medical insurance, right?

Do I have to report his B-2 visa status? I wonder why.

His parents only plan to have him stay here for 6 months and to catch up English. Thanks for your reply.