Bought a new home, question about the softeners in it.

I've been in the house for a little bit (built in '03), and had a few questions about the softener setup.
It has a dual tank setup, autotrol 255/460i on the salt tank, and an autotrol 255/440 on a bleach water tank. My first question is whats the purpose of the second tank setup/bleach water, just purification?
Also, the 255/440 control unit has a few stripped teeth on the day counter and the control cam is broken (not opening the brine tank valve).
Would replacing it with autotrol 255/760 logix be recommended? I was thinking put the 255/760 on the salt tank and move the 255/460 over to the bleach tank.
Also (last question, I promise) Would it be a good idea to replace the resin in the tanks while I have the controls out?

Thanks a ton for any help/recommendations.
Will