I think cherry shrimp are an excellent choice. They are pretty hardy unlike the others such as crystal shrimp. Also, even if you do plan on adding fish sometime in the future it's probably best to establish your shrimp colony first, starting with about 8 shrimp. They will be less prone to stress and any fry that hatch will not face predation.
There are a few substrates out there, such as Aquasoil, that seem particularly beneficial to shrimp. I know that ADA, Seachem, and fluval all produce this type and it has the added benefit of keeping your pH down. Whatever you choose I would keep it dark and fine grain to allow for full coloration and natural grazing behavior. I would recommend at least an inch in depth at your shallow point (if you're going to slope with your aquascape)
Cycling beforehand is important as shrimp will most likely not survive through an in cycle. A member on this forum, Diana, has posted several great fishless cycling instructions which I highly recommend looking up. The only thing I could possibly add to those would be to make sure whatever source of ammonia you use to cycle does not have surfactants (i.e. Soap) listed in the ingredients. Some stores; target, Home Depot, and lowes just to name a few stock bottles simply labeled Ammonia yet still have surfactants. Good rule of thumb is shake the bottle: if bubbles collect at the surface it has surfactants. I found the bottle I used at a local hard wear store but I've read several other posts where Ace hard wear carries the kind you'll want.
Lastly, when reading up before starting a cherry shrimp tank of my own, I had found several posts where the ability of the shrimp, because they have such little bio load, to maintain the cycle was questioned. I luckily(???) had a few snail egg clutches hitchhike into my tank while cycling and their population somewhat exploded which I believe attributed to my steady cycle. Hopefully others with more knowledge on this than myself will chime in.
Fluval specs have really great oversized filters and I think was a good choice!