Process of converting from H1B visa to H4

I am currently on H1B visa and my spouse is also on H1B visa. I am planning to leave job in one month and want to take some leave from working and just want to handle household work for sometime. So, planning to move H4 visa as on H1B, I have to go out of US. How easy is it to move to H4 visa? What is the process? Can I stay in US while my H4 visa application is pending? Also, how soon can I file for H4 EAD application? Can I only apply for it after getting H4 visa? My spouse had I-140 approved.

You will need to file form I-539 change of status from H1B to H4.

Yes.

You can file form I-765 for EAD along with your change of status application so that they will both process at the same time.

You can also change from H1B to H4 by simply travelling out of the US to your home country and get H4 visa stamping done using the copy your spouse H1B I-797 and other H4 supporting documents. You may be eligible for dropbox if you hold any US visa in past. This policy update is in effect till 31st Dec 2022.

https://travel.state.gov/content/travel/en/News/visas-news/important-announcement-on-waivers-of-the-interview-requirement-for-certain-nonimmigrant-visas.html

I would suggest hiring an immigration lawyer to file the change of status and EAD applications if you do not have enough knowledge of filing out the forms and the documents required, just to make sure you don’t file the application with any errors that may create issues with USCIS processing.