Primer on H4 please

[indyanguy]

Can someone give me a primer on the H4 visa? I am on H1 (visa from Co. A valid till 2007, working for Co. B). I am getting married in May 2006 and would like to get info on what docs are needed for H4 (she has had her visitor visa rejected earlier, would this pose any issues for H4?).

Also, general info on the H4 Visa regarding SSN, obtaining drivers license, restrictions, when she could change status from H4 to H1 will be really helpful

Thanks everyone