You do not need an attorney to file for joint simplified divorce. However, there are strict guidelines before you can qualify. Please review those guidelines: http://www.cookcountyclerkofcourt.org/?section=SERVRESPage&SERVRESPage=7065 You will file in the county in which you resides, not the county where you got married. You cannot get divorced on a walk-in basis. Divorce might affect your application for cititzenship so you will want to ask that question of an immigration attorney.
1 File in the county you reside
3 Repost just your third question in "immigration" on AVVO
The answer given does not imply that an attorney-client relationship has been established and your best course of action is to have legal representation in this matter.