PERM awaiting H1B maxout COS

Currently, I am on H1B visa and my visa is ending on 12.5.2020, my company will be filling PERM this week. My company is willing to wait until PERM and I -140 is approved and meanwhile have recommended to move to dependent status or tourist visa. I had following questions regarding my scenario:
1.I94 and visa: I94 is valid until 11.08.2020 whereas visa is valid until 12.5.2020, what date to consider for the last working day; how long before should I stop working for the company? When should I apply for Change of Status?
2. Change of Status : My wife is currently on STEM OPT and has H1B approved (I797B) through consular processing (June 2019) but does not have the H1B visa stamped on her passport yet. Her I94 admit until date shows D/S. Should I be applying for H4 or F2 or B1/B2? What is the best option given this scenario?

  1. What would be the best case scenario for conversion back to H1B once I-140 is approved?