documents required-10 years long residence ILR set(o)

[iAmirul]

Hi I am completely new in this forum. I need some advice regarding the problem below.

1. In December 2012 I will be able to apply for ILR under 10 years long residency with student visa for 8 years 10 months and rest on psw. In Mar 2008 my son born in UK and because of the midwife and hospital asked me to apply for child benefit, I applied and benefit office started giving me that. In Nov 2009 I wrote a mail to HMRC to withdraw the child benefit and explain to them I am not entitled to and I am happy to return it back. I paid them back whatever HMRC paid me. they provided a clearance letter also.

My question is
1. Will I have to explain in the set(o) application form about this?
2. Will it make any problem to get my ILR?
3. What could be the worst ting can be happen in this scenario?
4. Is there any law to refuse my ILR based on the above?

Please Advise me...I will be very grateful ....