Child visa needed?

I am a UK citizen currently living in the USA. My wife is American. My 4yr old son was born in the USA and has a US passport. We have been living in the US for 11yrs.

We are planning on moving to the UK to live and work.

1. Do I need to apply for a visa for my son? If so, which form? I cannot find any details on forms for dependent children and none of the forms seem to have instructions on what to do for your kids.
2. Or does he just come under my wife's application?
3. Or is a better solution to obtain a british passport for him and then only concern ourselves with my wife's visa?

Are you a British citizen by birth / naturalisation or by descent? If the former, then your child is British by descent and may apply for a British passport at the British High Commission in the US.