I have a weird water change system - my main fish tank (100L, HEAVILY planted) gets water changes with conditioned tap water, but my other tanks get water changed with the water from that main tank (they're all 20L tanks). The plants probably do most of the conditioning work for me, and my driftwood reduces pH to about 5-6, so I don't add anything to the water when it goes into my shrimp tanks. This method works AMAZINGLY for me.
In terms of ammonia... well... PLANTS! The plants basically make it so that I don't have any ammonia, nitrite or nitrate problems either. So, I guess if you have a fish tank that can play the role of the 'mama tank', so to speak, then try that.
In terms of specific conditioners, though, I've heard great things about prime, but honestly API Super Strength does it for me. I'm only halfway through the bottle after a whole year, so it ends up being super cheap!
I don't usually add mineralisers, but that's a personal choice. It honestly depends on the shrimp you keep and the parameters of your water out of the tap.
Hope that helps mate!