K.P.
Couple of thoughts...
1. New York State does not recognize "giftedness" for special education purposes, so do not request testing through the school. There is no need for you to know your son's IQ score , which is all the information you will gain. This testing is extensive and time consuming. Unless you feel that your son has an educationally disabling condition, the testing is not necessary. You can always elect to do so privately if you want the information.
2. Skipping grade levels is not always beneficial. While your son is academically advanced right now, socially he is likely to struggle with older children. It may not seem like a big deal for an 8 yr old to be in classes with 10 and 11 yr olds, but it is a big deal to have your 10 yr old with teens. Developmentally, very challenging and often causes social isolation and major social problems in middle and high school. Will you allow him to extend his curfew at age 11 or be in a car with a 16 yr old when he's 13?
3. Look into the local community colleges and universities. Many offer "kiddie college" opportunities after school and in the summer. I have seen courses in science, art, music and other enrichment opportunities. You are more likely to have him "skipped" a grade in an afterschool program than in his school.
This one is going to be up to you to explore. At this time, school districts are largely reducing programs and are not likely to add enrichment opportunities in the near future. Keep in mind that you can make anything you do into a learning opportunity.
You can also speak with the teachers and ask if they are able to differentiate for your son. Many teachers think that gifted kids need "more" when in actuality they need "different". For example, when the third graders are doing a research project on ecosystems, ask the teacher to enhance the assignemtnt for your son. Maybe he can explore how rainforests and deserts are similar and different rather than researching one or the other. His presentation could be more complex and extensive.