Cap exempt H1 b to cap subject H1b can I leave the country when new petition is pending

Presently I’m working on cap exempt H1b and have found an employer to file cap subject H1 b petition in 2020 cycle. My questions

  1. will I need to get a new stamp on my passport or will my old H1b stamp work after October 1st?
  2. while the Cap subject petition is pending can I travel outside of USA for vacation between April1st-October 1st (Last week of May to be specific) since I will be working with my current employer until October 1st and will be re-entering based on my unexpired H1b visa?
    Please advise if anyone has any information. Thank you.