Any servo should work aslong as it's the right size, of course. This means micro servos. Theres more to choosing servos than size though. The faster the servo you get for your cyclic, the quicker your helicopter will respond to input, but the less overall torque (or holding power) the servo will have under high load. This really isn't a problem on micro FP birds like the 22D as they really don't exert enough torque to affect the servos.
You CAN mix and match servos between the cyclic and tail, infact most people do. What I WOULDN'T do, is mix servos for your cyclic control, as two different servos will most likely have different movement speeds and torque, resulting in the control feeling "wierd" probably.
If your tail servo is working fine, then i'd leave it unless you have reason to upgrade it. Obviously, sticking a better servo on there will work alot better for your tail control, but unless you're having control problems, just replace what you need to. If that means getting 2 matching servos for cyclic, or just one servo for the tail, then do that, just don't mix servos for your cyclic control.