till what time can i work after i have applied for h4

my current visa is L2 and it expires on Nov 2012, and i have to apply for h4 as my spouse have applied for h1.

My Question is after applying for H4 till what time i can work i.e i should stop working immediately after applying H4 or i can work till my H4 gets approved.

My Other concerned is if my husband applies for H1 transfer while my H4 application is in progress will that affect my H4 application.

Thanks in advance