The first bit of advice that I would give you is to start with the best cherry shrimp that you can get. The price of fire reds (even newer PFR) is getting so low that they are easily affordable.
Otherwise down the road you will decide you want a few dark/solid red ones and then you will be stuck either maintaining multiple strains or mixing them (which will mean that you can't sell the extras at the higher grade).
Azoo has undergravel circulating pipes that I have seen recommended for slightly planted (or shrimp only) tanks that seem like they would suit what you had in mind for the future 12G tank.
Both shrimpnmoss and mordalphus have shrimp tanks set up along the lines of what you are suggesting (using UGF that are pipes or tubes and which are powered by external canister filters). shrimpnmoss has a pretty good diary of sorts describing it over at shrimpnow and mordalphus has a thread going right now in the inverts sub-forum here about how he just set up the filtration in a re-done shrimp tank. Just some info to help you on your way when you get around to setting up a bigger tank (with UGF).
For cherry shrimp the stratum should be great. You don't need to really soft water and low pH for Neos to thrive so Fluval Shrimp Stratum combined with tap water should work great.
If you have the shrimp nano-tank in a climate controlled room away from windows and doors (drafts) you probably don't need a heater. Finding a nano-heater can be a PITA.