I am currently in USA on H4 visa. I got my H1b petition approved (new petition) in May 2009. My employer did not file for Change of status while filing H1B visa becuase at the time of filing i was not in USA.
1)I want to know if i can file for change of status now as, i am in USA on H4, without affecting my approved H1b petition
or
do i have to go out of USA and get H1B stamped before i can start working?

2) if i can file for Change of status, does this require new filing of H1b petition.

3) What are the chances of getting Change of status approved.

4)if COS can be filed, can your firm help me file.