When I-485 is pending you can stay in the US legally. I-485 itself, however, provides no status.
EAD gives you the right to work. There is no obligation to work. EAD (used or unused) does not provide status.
Once you no longer work for an H1 employer, you are out of H1 status. Unless you get another H1 approved with a I-94 at the bottom, you will have no status. You will be legally present based on the pending I-485.
It is not clear what category your I-485 was filed in, but you need to make sure you maintain elibility for your green card especially, if you no longer have status.