Can employer cancel H1B petition? Can I file new petition thru another employer? Lottery details

My Employer filed H1B petition for me, and it got approved for three years (from sep 2014 - sep 2017) but stamping is not done (obviously not working in US yet). I’m moving to another job. My Employer told they will cancel my H1B petition. I just have receipt number, employer holds all other details.

My questions are:

  1. Can they cancel.?

  2. If I file a new petition from other employer,

2.a) will it be considered new altogether.?

2.b) And again will it falls under lottery or will it be waived off lottery.?

2.c) For new petition, what details I should provide related to old one.?

2.d) Can I file a new petition even if old petition is not cancelled or expired.?

2.e) Details related to lottery for later petitions

Please answer my questions. Thanks a bunch.!