I have three filter housings like this http://123filter.com/catalog/images/HC14.JPG
with appropriately sized (10x2" in my case) 5 micron carbon block filters (I was initially using a 10u at the first stage but haven't noticed any lower flow/life with all 5u, but my house has all new plumbing (pex with minimal copper fittings and no rust chum like the old pipes had) and my water is very soft from the tap. A carbon block filter is usually something like coconut husk charcoal, broken into bits, held in a filter housing with some floss and a plastic shell. They attract and absorb free ions in the water, like chlorine, chloramine, fluoride, sodium. There are larger and smaller filters (the biggest ones are 4", which is huge), they're rated for whole house use for 3 or 6 months, so they're durable and have good longevity. My inlet just comes in from my python fill hose so I can still mix in warm water, and most (if not all) of the concerns about using water heater-ed water to sparge your fish tank water go away because it's also being filtered through activated charcoal. Is three stage necessary? Probably not. Should you change the filters more often than I do (which is twice as long as they list for whole house use, even though that's not really how carbon works -- it's still absorbing crap out of the tiny bits of air that get into it when I' not using it and becoming less effective) maybe.
When you google a type of shrimp you'll usually find several breeders who list their "TDS" (total dissolved solids) in their tanks. Usually the bee shrimp, cherries are less picky. Almost all of my fish (a 75 goldfish tank, a 29 shrimp tank, a smaller species 55 tank, and a 20L hospital/plant tank) live in ~120 tds water, I judge their water change schedule on when the TDS goes above 160. The plant tank obviously I'm less stringent about, it goes over 220/240 tds pretty regularly. I don't use it as an absolute water quality measurement like proper mars kh or gh drop test, but the combo of the carbon filtering and the TDS monitoring I use it to make sure my in-tank water is consistent from week to week, especially when the city changes from lower to higher alkalinity sources (our local basin catchment or the well field). I got mine on amazon, it's a pretty common TDS meter, well reviewed HM digital, I think I paid $13 for it. I've also got a "high resolution" pH pen I got for the same price, less well reviewed. I still haven't used the calibration fluids on it so again, I use it mostly to check day to day/week to week trends instead of absolute values.
Sucking out a single baster full of water into a testing vessel one time and jamming in two meters sure beats doing 4/5 drop tests. Since there's no reagent/obeservation other than waiting for the measurement to settle out, you can test as many tanks in a row as you have old jam jars.
As far as how much water to change and how often there's as many ways to do it as there are fish to keep. Lots of shrimp keepers do monthly changes, Specifically remineralized RO or Purified Spring water only, and RO only to top up. As long as you can measure what you're doing to the water Pete Mang (lotsoffish.net) has a pretty good article about water changes and nitrates and the point of homeostasis for water (numbers based on weekly changes). The upshot is basically, the amount of water you're changing out directly relates to the final/normalized nitrates in your tank, it's significantly better over 25% and then diminishing returns kick in after about 75%. He personally espouses 75% water changes every other day but he's also an insane person (the good kind of insane but still insane). I think the part that's critical to his success (and mine) is non-ionically filtered (non ro/di) water that is the same temperature as the tank (and even on that I'm not a stickler, sometimes I'll let my 72 degree danio tank get some 68 degree water and watch them spar and spawn all day and my shrimp don't seem to mind that temp either but I try to keep it closer to 70) and a consistent and frequent water change schedule. I believe Mang takes care of the water temperature thing by having an aging tank/water holding vessel with heating that he fills from.
Again, I'm "about twice a week" or basically every four days. Depends on if my calendar notification motivates me out of my blanket full of farts on Sunday or if I put it off. I also use lids on all my tanks except my room temperature tank (the goldfish) to make sure I have as little evaporation between changes as possible, I don't like the idea of the water getting sour any faster than it has to.