I think you're partially right. This is the best explanation I've seen for comp picks:
NFL Compensatory Picks Explained
From this, and other things I've seen, the amount of signed/lost players is #1, followed by where they fall on the ranking of FAs. So, for example, if we lose 2 players in FA and sign 2 within the proper period (I believe March - End of July), then we don't get any comp picks no matter of contract size.
But if we lose a huge FA and a minor FA, and sign 1 minor FA, then we'd get compensation for the huge FA. THIS ONLY APPLIES TO SIGNING UNRESTRICTED FREE AGENTS, not players who are traded or cut from teams. This might not be right, but I've seen this in many articles explaining how comp picks work.
If we only lose Bell and Jesse James, and sign 2 UFAs, then I don't think we get any comp picks.
I haven't seen the numbers for JJ, but with the talk about him potentially getting more than expected, we could be looking at a 3rd for Bell and a 4th or 5th for JJ if we don't sign players that cancel them out.