I have a question about marrying a B-1 immigrant

I am an american, and my Czech girlfriend has been living in the USA for about 8 months with a B-1 VISA as a nanny. The lady she works for is very mean to her and doesn't pay her (though her contract states she is to be paid). My girlfriends VISA expires on December 31st.

We think we have three options to keep her here.
One option is to sign a new contract with another person and extend the B-1 VISA for another 6 months.
Another option is to find an employeer willing to hire my girlfriend, and apply for a work VISA, which seems like it would be a difficult thing as I don't see a real benefit for a company to hire an immigrant.
And the last option is to get married, as we've already talked about it.

Now, related to marriage, I have some questions.

When I ask for her hand (if I do it before her current B-1 expires), and we are "engaged", how long can the engagement be before we have to marry?

When we file the necessary paperwork (what...a Fiance VISA???) for marriage, can she work, or does she need to file additional paperwork to get a job, I.E. a work VISA? She would like to move in with my this coming January and find a job...maybe at a nursing home as she is a nurse.

When should we begin the process for marriage before her B-1 VISA expires on 12/31/06?

Thanks so much for any help,

Adam

BUMP