My STEM OPT extension is pending, can I file change of status to H4 with I-765 application?

Hello, I have applied for STEM OPT extension and it is currently pending with USCIS. My spouse has I-140 approved, can I apply for change of status to H4 with I-765 application while STEM OPT extension is still under process and would it have any impact on STEM OPT extension process? Also can I keep continue working while COS is in process?
Thanks for your time to review my question and appreciate your help!

Yes you can apply for change of status. OPT EAD application may keep processing in parallel, no issues.

Yes, you can keep working during the automatic 180-day extension period while your OPT EAD is being processed but have to stop the same day of H4 approval if your H4 EAD is not approved with H4 and can only resume once H4 EAD is approved.