I'm amused by the fact that you set up a Youtube Channel for shrimp keeping!
You have a great voice for doing videos! Really catchy and amusing! Cat is also entertaining!
Disappointed that the shrimp came from Aquatic Arts. They sell imported shrimp, and unfortunately, imported shrimp are known to have ellobiopsidae, which is a parasite that looks like a green fungus growth. I have heard that it can take up to 3-6 months before you even see any signs of this parasite on your shrimp... so hopefully, your shrimp are healthy!
Shrimp tanks turned out great! I do hope those rocks are inert!
Neos really do best on sand with GH and KH though...
Don't know if it's true, but I keep seeing people say that Tetra SafeStart and Marineland Aquarium Bacteria are the two top products to help cycle a tank. I don't know how Seachem Stability compares, but have been curious.
No experience with Bacter AE, heard great reviews about it, but from my understanding, it's not the same as bacteria meant to cycle a tank.
If you feed your shrimp, you shouldn't need to feed them more than once a week... unless you want to provide supplemental feeding for the babies.
The Fluval Shrimp food can potentially enhance the color of the shrimp, or turn them weird colors... so if you feed it, be aware of that. Not recommended if you want good colored shrimp that reproduce with good colors.
Thermometers.... those can be fun! I put 4 different ones into one tank. They all read differently... You can go up to 86° F though during the cycle, then lower it once you are ready to add shrimp. You want to get the temps down to 68-72°, although some people actually do have better success at keeping Neos at 76-78° range. It's good that you lowered the temps!
If the shrimp are imports and not home-bred, then it's quite possible that they went through a lot of stress with changing water parameters and shipping. If Aquatic Arts bred them, then it could be due to a change in water parameters and some shrimp just can't handle it all that well.
Each bucket should have a TDS of 150, if that's that's what the shrimp prefer and it's at the right GH. If you take two buckets of 150 TDS and add them together, they are still going to be 150 TDS. You aren't adding more water, or more minerals to the water to change the parameters. If you have water evaporation and the TDS of the tanks rises, then top off with RO/DI water. If TDS rises and you want to do a water change, you could, in theory, remineralize the new water to lower TDS (as long as parameters are ideal or slightly high), so once you add the lower TDS into the tanks with higher TDS, it equals out to the ideal parameters that you want.
If you really are planning on keeping Neos and Caridinas, then I'd personally recommend a GH of 6 with whatever TDS that comes out to. Would not go below 5 GH. Keeping both species in can sometimes be difficult as one species may "out-compete" the other, depending on the water parameters. That is, one could breed better than the other species, so one species may experience a population boom where-as the other may not do quite as well.
If you can find a USA breeder who keeps both species in similar parameters as to what you've got set up (aka no Aquatic Arts!), then you'll have a higher chance of success of keeping the two species/colors that you desire in your tanks.
Overall, started out great! You've done a bunch of research and have received a lot of helpful suggestions! So short end of things, looks like you've got just about everything covered! I look forward to future updates!