Attorney should know what to do. If he/she does not, well, you better get another one.
Technically, company representative (usually someone from HR) should interview the candidates. They better know what to ask and how to document everything [also, note it is illigal for you to attend the interview]. So, the Attorney should probably talk to them before the interview and explain the important points (which depends on the strategy he/she has chosen for the case).
It is exremally important to prove that candidates do not qualify for a reason that goes smooth with your LC requirements. And it should also be a just one. E.g. you can't say they are not tall enough [unless u'r applying for a basketball team]. Also, if the number of replies is high, even if all of them are disqualified reasonably, it will probably still look quite suspicios to SESA (especially for a RIR case). You might want to pay more attention to this matter. This is the most important part in Company sponsored LC/GC process.
I've not heard INS following up with ALL candidates though, they probably audit some cases [who knows on what basis].