Congratulations man. Catalina 22s are a lot of fun.
I've done both the keel cable replacement and a rudder refairing on mine. Here are some pics and things:
Rudder Part 1
Rudder Part 2
I have mine set up so that the rudder can't hit the prop, at least when the rudder is down. When motoring in very shallow water where I have to kick up the rudder, there's some danger, but I just pay attention. Some people make little extensions to the cavitation plate of the motor that extend past the prop as a guard.
The cable is an important thing to check out because a broken one can be really bad news, but mostly I'd suggest you just sail it and worry about the non-safety related maintenance for some other time.