F-1 and J-1 are similar, I used both to go to school in different events, both of them, in order to maintain your status on SEVIS, you need to be full time unless it's your last year and your remaining classes don't add up to be full-time.
For payala: SEVIS (can't rememebr what it stands for) is a system that keeps track of each international student, they major, how many classes they are taking, work authorization, addres... everything is there.
I told the international advisor at my college that I was adjusting status, so she sent a message through SEVIS about my immigration situation right now and she cancelled my F-1 status. You guys should do that too, just in case the USCIS checks on your F-1 or J-1 status. BTW, when you go to the interview you should bring your transcripts or something that proves you weren't out of status.
I am not sure if you can work on campus before your EAD, same thing for J-1. But I believe you might have to wait for the EAD, talk to someone at your school, or whoever processed your J-1.