Full-time with H1, part-time with EAD, any paperwork necessary

To Xiaobaotu and other experts,
My I-485 is pending. I am on H1B with my full-time job. If I use EAD for a part-time job, my understanding is that I would lose my H1 status. Am I right?

After I use the EAD for the part-time job, what kind of paperwork is required from me, my current employer and the company providing the part-time employment?

Thank you very much!