From my experience the GH And kh will peak at some point and won't go much higher. As you do water changes it will remove some of the waters hardness and it sort of balances out.
The only downside to crushed coral is it raises the pH of the water. The kh has direct correlation to the pH and is also a representation of the GH value.
I found that its an easy way to keep neocardinas because they will acclimate to higher pH values and do well with the added GH. You only run into issues if you are keeping fish that thrive at a lower pH, like tetra species or other tropical fish. Although they will live in higher pH you will have reduced breeding/ coloration & also opens them up to disease and shortens their lifespan a bit.
If you have hair algae most people will tell you its due to high phosphates and excess nutrients or lighting. Best way I've found to combat it is manual removal and dosing liquid co2. Excel and similar products have been invert safe in my experience but I recommend half the dosage just to be safe. Also use with caution, I see you mostly just have moss in your tank so it may not be fully absorbed and may lead to more algae issues.
Another note: most fish will eat anything that fits in their mouth. Some are more aggressive than others.
I've also found that moss grows and resists algae much better with some water flow on it.
Also with 10 or less shrimp feeding should be very sparse. With moss and algae in the tank they will always have something to graze on. Overfeeding will lead to molting issues. Molting issues leads to dead shrimp
My advice would be limit factors that could cause them to die. Feed less, get a stable pH and definitely more plants if you want your tank to benefit from co2 injection. Shrimp are sensitive and even the stress of water changes can cause them to die. Striping means they are ready to breed and they should have yellowish saddles in their upper back behind their head. Once that happens the eggs will move down to their legs and are ready to be fertilized. Once fertilized you will be able to see black spots on the eggs which are their eyes. Wait about 3 weeks and you will have shrimplets. Once you can see shrimplets in the tank make sure to be vary careful with water changes so you don't suck them up, they are pretty tiny for the first few weeks.
From my experience the shrimplets tend to be a little more hardy because they are more used to the water conditions you have provided. And their exoskeletons will grow in a more linear pace compared to the adults or sub adults that you received which could have came from random water conditions.
Once you get past all that you can think about adding more cherry shrimp to diversify your gene pool and then you will be on to your next project, maybe even the harder to keep cardina species.
As far as snails go, some find them an eyesore but I find them beneficial and interesting. If you ever feel they are out of hand you could pick up some assassin snails, but beware they will decimate the population of your snails. And you should always have a cleanup crew in there, otos are awesome but can be very sensitive. In my shrimp tank I decided to go with nerite snails because they are peaceful and don't breed if you just have one.
Please excuse the wall of text
This site is great and you can find plenty of information on here.
I'm sure others will chime in with their experiences which may differ from mine, its all a learning process and can be very rewarding!