I just came across this forum and really liked the help the people on this forum give. I want to apply for British citizenship for my wife, myself and my son and want to do at minimal cost

December 2004: Me and my wife came to UK. I came as my wife's dependent
December 2005: I got my own independent work permit
July 2009: My son was born in the UK and we got his indian passport
December 2009: My wife and son got their ILR
Jan-March 2010: My wife and son were out of UK.
December 2010 : I got my ILR
My wife and son are eligible to apply for Brithish Citizenship. I want help on following questions:
1. Have they met the 90 day rule - Can you please let me know that although, they were out of country for 90 days from Jan to March 2010 if they apply in say Feb 2011, they will not breach the requirement of not being out of UK for 90 days in last 12 months.
2. What will the fee I will have to pay for the joint application of my wife and son. Will it be £1,010?
3. Will I have to fill out 2 AN forms for my wife and son - I could not find any form for a joint application
4. Can I apply along with my wife and son for citizenship - I have been on country for 6 years although have not held an ILR for 12 months. Just want to save £780 for a separate application
I will really appreciate your help on this.