Child benefit and documents plus question about EEA2

[ukbaby]

Hi,

I was on EEA2 and recently got ILR.
I would like apply for child benefit for my 2 children. One is 3 yrs old and another is 3 month old.
Question 1: When I was under EEA2, Were I subject to immigration control? If I claim by ILR, they can not backdated to 3 months because I just recently got it. I also can apply under my EEA partner, but do not want to have any affect with future his EEA3 and my parent EEA2 application.

Question 2: If 2 children, can I claim for 1 child and my partner apply for another child? I am on maternity leave, not sure if will go back to work. He is self employed. Because we want to protect state pension for both.

QUestion 3: I called HMRC, they told me all the documents need to be original including my passport or BRP...I read some people send photocopy of BRP only, Is that working? I really do not want to send original and can not travel...

Thanks X