H1 Transfer, Will I need stamping again?

I got approved petition this year on Oct 1st, and will go to India soon to get my passport stamped. My question is -

  1. Is it OK (or possible) to transfer H1 to someother employer before even having it stamped?

  2. After getting stamped, then if I transfer H1 to some other employer, will I need to stamping again?

Pls let me know.