With regards to holding him out until the IEP is in place, in the bad old days of our district (3 years ago), they refused to grant an IEP on grounds of inconsistent attendance. This was for a child who needed OT services, but had missed a lot of school with scarlet fever.

I get the need to hold him out, but be aware that a school that might be disinclined to help can use inconsistent attendance a grounds to deny services.

You just had neuropsych testing done -- can that tester be brought in as an expert to educate the teachers?

Lawyers quickly beget other lawyers. Can you find an advocate instead? We've had great luck having a dispassionate person in the room who can keep the gifted and disabled aspects of my children in her head at the same time.