A potential employer (A) in SanFran area is willing to sponsor me for a green card, but the project he wants me to work on will last for about 6 months or less . Is it possible for that employer to file the green card application? Employer (A) is willing to pay the expenses for the green card process knowing i will work for him for only 6 months or less.

I currently have H1B visa that expires in March 2011 with another employer (B) in Philadelphia. Employer (B) is considering filing a green card for me, is it possible for both companies to file 2 green card applications for me in the same time?

Filing a green card application can be for a future full time position, can i transfer this application to another employer after the application has been filed? and when?

Thank you.