L1 to H1B tax filling question

[meetasn]

Dear Immi Gurus,

I am an L1B holder working in US since Jan, 2003. Converted to H1B in Oct 2007. Started working for H1b From 2008 Feb. Now I have two w2 forms.
My wife & 2 kids (both are Us citizens)

Family (spouse and 2 kids) went to india 2007 Dec. My wife joined back on 2008 Sep. But both kids are In India and will be joining me sometime on March, 2009.

Kindly advise me for filing 2008 US tax returns.

1. What will be my filing status ?
Eg: Married filing joint return OR
Married filing separate return

2. What do I need to reply for the following question:
"Will you claim an exemption for your spouse when you file your tax return? "

3. Will I get Child Tax Credit (since my kids re in India) ?

Your advice will be appreciated.

Thanks
Sagar