I am currently running a grow using self watering pot bases. I am in soil with dry fertilizers and it's going great. Probably some of the healthiest plants I've grown yet as correct watering practices is one of the hardest things to get right imo. That being said, like numbers said I only add water to the base and its fine for me. I've seen the same done with autopots and hempy buckets.
As far as nutes, they will wick up too. The top layer stays dry and is where the salt build up will occur and that's normal. The whole purpose of autopots is to supply the constant but correct amount of watering/feeding. But like mouse said if you gotta flush it for some reason (over fed ect), it's gonna suck and take a lot of water to get rid of the salt build up.
As fat as recharge goes, I use it too, but mainly as a ph buffer or in the hole I'm transplanting to. It's not very water soluble and will build up in your tank. People do use it in the res though, I don't.
Just need to find what works best for you. There are some videos of people using them and a guy by the name of autopotamus is insane with it. He has everything in check though from environment to nutes pulling 1lb plants from autos in autopots. So if you can dial everything in correctly, you get great results.
Just my thoughts based on my experiences.
Best of luck! Happy Growing!