請教我見,Dan712 and other experts

Hi, My I140(NIW) is pending.My wife and son are in USA. I am going to file I485 and I131 myself. I have several questions when filling the forms. I do appreciate it if you could help me.
1. For form I131, part I, item3: How to fill the "Class of Admission"

2. Should I fill two I864 forms(Affidavit of Support)? One for my wife, one for my son?

3.For Form I864, PartII(Basis For Filling Affidavit of Support), Should I select

a. I filed/am filing the alien relative petition OR

b. I filed /am filing an alienworker petition on behalf of the intending immigrant, who is related to me as my-----.
Thanks a lot