I don't think they try to sign Rice until they see what happens in the draft first. I like Rice but his body has taken a beating. I'd rather give opportunities to younger players. I say if they draft a WR in round 1 or 2 then they don't bother with a veteran signing but if they don't do that then you go looking for a vet, and Rice would be the 1st choice.
Kearse, Harvin, & Baldwin...That's relatively solid. Add a 1st or 2nd round pick and assuming the rookie produces you should be able to handle an injury there. (Cough Harvin Cough).
I'd keep Lockette on the roster because of his value on special teams. There is your 5. If you want to keep 6, you have a battle between Chris Matthews, Taylor Price (2 guys they signed this offseason), possibly another rookie (either a late rd pick or undrafted free agent), and 2 practice squadders from last year; Arceto Clark or Bryan Walters.
I'm perfectly comfortable with this scenario.