L1A to H1 transfer after leaving the L1A sponsored company


4 years back, I came back to India after completing H1 stay of 6 years. Last year (2017) my company processed a new L1A for me, my passport has the stamped visa till 2019. Then due to unfortunate circumstances I had to leave that company. Now from last 6 months I am with a new company, Need your valuable answers for the following question

  1. If I rejoin the company is this L1A still valid?

  2. Is there any easy way to use this valid stamped visa to get a new L1A (new company)?

  3. Can I transfer L1A to a new H1 (Apr 2018), though I never traveled or used that L1A?

  4. Any use of this stamped visa, when I go for new visa interview be it (H1, L1 or B1)?

  5. When can the new company file a new L1A for me? do I need to work for at least 1 year to process L1A

Thanks for your help and appreciate a quick response