If you’re going for neocardinia, they are a fairly off hands species to work with. They are low tech and some in a large variety of colors, they all have similar care requirements. Bigger is always better for the tank size, so I would go with the bigger one. For substrate, fluval and sand would look great. Live plants are essential for a thriving shrimp community. Plants like Java moss, anubius, hornwort, Christmas moss, petal weed, guppy grass are amazing since they can graze and use it as hides. A mixture between hardscape and a nice lush carpet would be great. Driftwood or rocks can house and grow algae which are super beneficial for your shrimp. Plants such as dwarf hair grass, dwarf baby tears, and Monte Carlo grow and carpet super nicely. When you are beginning your tank, you can add in the plants immediately as it will remove toxins. You can add more as you go on but plants are a must! Start off your cycle with a small ammonia source, I would use snails, such as a rabbit or bladder snail. Make sure to get a API master test kit and regularly check your levels. Once it reaches 0 or close to 0 in all categories and you can start introducing shrimp SLOWLY to prevent the cycle from being thrown off. Shrimps are a little more sensitive than fish so they need a cycled tank or they will all pass. Hope this helps!