---No. Just wait. If 90 days has passed and you haven't got it, you can bring your receipt to the local office for an interim EAD issued on the same day. Make sure to make an appointment first with infopass.
2. If the lawyer can do it, I am willing to spend some money to the lawyer for push the process
--Your lawyer can't do anything for you on this matter. They have a rule. But usually it takes about one month. So take 90 days as the maximum, since you will be allowed to get an interim EAD.
3. I have applied I-765 under J2 status in Aug. According to the processing, my case (J2 I-765) will be permitted during one month from now on. If I can combine the applications them (J2 and I-485 I-775) into on case.
---No, can't combine the two together.