Could not help you with legal questions, but,

I think you need friends, school teachers and co-workers to say that you are a caring mom. Your current concern should be trying to get your son back. This is your highest priority. It is not the time to save money. Get a good lawyer. Some forster family can be quite bad for a kid. Don't try to figure out whehter your neighbor did anything illegal now. Of course, in the process of proving that you are a caring mom, you can mention your neighbor's attitude towards your son, i.e., she does not like him and thinks he is too noisy.

Feel sorry for your son and you. Wish the best.