Considering the age of the system, I would have recommended replacing the system. You got your moneys worth.
That being said, you should always replace the bottom screen when re-bedding a system. The system should be backwashed according to the manufacturers recommendation and must be adjusted for media type and water temperature. Fine mesh resin requires less water to backwash so if you did not adjust the Drain line flow control, you can easily lose a lot of resin out the drain during regeneration.
The old Autotrol valves have a clear check valve assembly on the valve. A safety float can be added to the system and will not affect anything. Assuming the valve is functioning corretly, the Autotrols are timed refill so they should put in a pre-determined amount of water back into the brine tank.
When was the last time you had your water tested? Do you have a hach 5B test kit?
Just use regular resin and intermittently clean the resin with a resin cleaner if you are not going to remove the iron prior to the softener. Since you have H2S, you may want to look at updating your system with some more modern equipment that addresses your water problems more accurately.
Also, the TDS and hardness conflict, can you get an updated water test?