Fresh H1 transfer before October 1st

I am on L1B Visa valid till October,24 2013 with Company A.
Company B applied for my H1B visa and I got RFE. Company B will send RFE response with a week or 2.

  1. If meanwhile I got good offer form Company C. Can I transfer my H1b for Company C before I start working for Company B.(My Fresh H1b is currently in RFE status).
  2. If I get the H1B approval on September 20,2013, Can I serve 1 month notice period on my L1B and join H1b company by October 20.
  3. I have approved I797 of 2009 for H1B with Company D. I got 221gon it when I went for H1B stamping and than never responded back.Can I use that petition for H1b transfer under cap exempt.