Once you get married,

She can apply I-130, I-485, and I-765 at the same time. I-765(EAD) will be approved within 90 days. If she doesn't get the EAD within the time frame, she is allowed to ask for a temporary EAD at the local immigration office. Once she gets the EAD she can work legally in US even though her OPT expires. It takes a little bit longer to get her temporary green card now because all family-based applications need to be sent to the Chicago office since Dec 2004. Based on the info on www.uscis.gov, it will take a little bit more than a year for the whole process. She is allowed to wait in US while her case is pending.

You will find more info on www.uscis.gov