CB is a need yet but we're primarily talking about a #3 guy there - whatever your feelings on Logan Ryan he played well enough (with safety help primarily, yeah) that as far as "starters" go Butler/Ryan is still a great starting point. Arrington was problematic but turned into a nice nickel corner that could ride slot guys, I think they can do a decent job of covering that role via present roster or the draft. Of course if they found a CB that could push Ryan, great! All the better.
RB is a more definite need to me - at this point it seems like they must think they're in a good position to get 1 or 2 guys in the draft that they think can handle the bulk of it, because there's no way they can think a returning Lewis and White/Gaffney/etc is good enough (right? Bueller?).
I was big on Forte going into FA but all things considered I prefer the Bennett pickup if they were going to drop $4-5m on one veteran skill position guy. LGB is still a possibility in the "kick the tires" and see what he's still got fashion but they have time to wait to see how he recovers as I would imagine he doesn't have much interest from other teams, nor does he have much interest in going elsewhere, based on his last FA excursion. He'll either re-up here post-draft/mid-summer or land in someone else's camp at the last minute I think.
Regarding the OL, I don't even know. There's reason to believe that the current roster as-is (even you, Marcus Cannon) will be better just for improved coaching, the statistical probability that the injuries will certainly be less, Cooper is talented and underachieved in AZ but could def win a job, and the two rookie interior guys coming in with a year's worth of game experience. I guess you just gotta hope that if that's the way it slants that the logic is correct. Certainly the backup T position just HAS to be better, but I'm not entirely sure that anyone still available as a FA or any rookie would in any way guarantee that more than what we already have. Will be interesting to see how much draft capital, if any, is spent on the OL.