There are a lot of good callers(both hand, and electronic) out there. The tried, and true cottontail distress is hard to beat. I use a Fox-Pro, which is just a little spendy, but well worth every single penny, and then some in my opinion.
On the 22 magnum question, I know some guys will say yes, it's plenty of gun for coyotes. I'll be the first to say that the 22 magnum is amazing for what it can do when everything is perfect(calm/right angle, etc.). The problem is, "nothing" is ever perfect when it comes to calling any predator.
For one thing, the animal is already pumped up on adrenelin when he comes in. Everybody knows how hard deer can be to put down once they've got worked up, and a called in predator is the same way. I've seen foxes take a solid lung hit at less than 30 yards with the 22 magnum, and still run for 50 yards before falling. Even so, I still consider the magnum to be the best fox catridge as far as fur friendly, but still potent enough.
Take it from a die hard predator caller. Use a bigger gun for coyotes. I use a 22 Hornet now days for nearly all my calling stands. It's a bit much on foxes(have to be careful of the shot angles), but it works great on close range coyotes, and bobcats.
