What I heard is different from these:
1. If current status is F1-OPT, after submitting I-485 and EAD application, no matter you use it (EAD) it or not, the status will change to AOS. If current status is H1, you can keep H1 status after submitting I-485, but if you use I485-based EAD, the status will change to AOS. This is based on that H1 visa is the only non-immigrant visa that can be kept after submitting I485.
2. If No.1 is correct, for F1-OPT, I am not sure whether you can still apply H1 or not after submitting I485, since your status is AOS now, not any non-immigrant visa.
I also have the same question about this OPT-I485 issue, but I am not sure the above answers are correct or not.