I am on H4 and applied for H1 2010 quota which is still pending. My husband alone has EAD but not used. He got his I485(EB3, PD jun2007) filed before we got married. He wants to use his EAD now, So I want to go for H4-F1 COS while my COS H4-H1 is still pending as I realized it is very difficult to get H1.

1. I want to file the COS H4-F1 while my husband is still on his H1. As soon as I file COS H4 to F1, my husband wants to start using his EAD. If my husband starts using his EAD then what would my status be while my H4-F1 COS is still pending?
2.Can I go to School while COS H4-F1 is pending? If yes, what will my status be until COS H4-F1 gets approved as my husband will have started using his EAD by then?
3.How early can I apply for a COS within USA H4-F1 for admission term May-2010?