You sue
1. FBI director,
2. USCIS director,
3. DHS director,
4. USCIS service (either local or center, depends on where is your case stuck) director,
5. US Attorney General
You will server all the above, plus AUSA
>2)請移民律師,還是其它律師
Immigration lawyer only.
You can do pro se, if you are either poor, or have confidence to understand all the jargons and you think you are ok in front of the judge and UASA. And you have a lot of time to prepare for yourself, do lots of home work to study the required law. Not to discouvage you, actually many are going through Pro Se.
Or get a immi lawyer, who is experienced at litigation.
If you have specific questions, just ask. Many of us here do help each other on daily basis (no charge :-)