H1b Maxout while Perm in process

Hello, please review the below case and chime in with few suggestions
My current H1b Petition will end on 1/12/2020, I can recapture 20 days for 6 yr max out.
Perm is under process and expected approval per current trend is the end of December 2020.
I am getting contradicting responses from various people/attorneys, can you please guide what should be the best option for me

  1. Is it Mandatory to maintain few buffer days before max out and use them to file perm-based h1b extension?
  2. Should I apply for the extension to recapture the remaining days?
  3. Should I change to H4 on 11/30/2020 or earlier (My Spouse holds H1B and her employer would file an extension in a couple of weeks)
  4. If I use all the pending days and if I don’t get through the i-140 stage till then, Can my employer apply COS to H1 + extension based on 140 OR should my employer file a fresh h1b through a lottery after 1 yr. gap.
  5. Do you advise, I stop working mid-November from the current approval date (1/12/2020) , to have some residual days and don’t bother about recapturing any days.