I am on F1 visa and my wife and son arrived USA in November 2010. I have few questions about filing my tax return

1) Since I am in USA for more than 2 years, I pass the 183 day rule to qualify as resident alien tax status. Since my wife and son came to USA first time in November 2010, which 1040 form I should use when filing tax return for 2010 (1040 NR OR regular 1040)?

2) Can I claim my son as dependent even if he stayed for only a 45 days in USA during tax year 2010?

3) Do I need to apply for ITIN from IRS for my wife and son?