Yes, we should sign all three, IMHO.
Okafor to 67: Looks a little much to me. If we can convince Emeka to 55-60 level, we'd do a good job. But he'll try to get max.
Wallace to 47: Just the fair number, I think. Not so much, not so little.
Carroll to 25: If some team offer him that 25(MLE), then we'd match it(I know he is unrestricted). But I guess we can tie him for 20 mils/5 year deal.