I know I'm a bit late on this one, but, I'm setting up a shrimp only tank of my own (in my office, 'cause I get bored!)
I'm definitely going for a sponge filter rather than an internal/external media filled filter. If you are using one of these filter types, you really must make sure any intake sections are covered over as even small adult shrimp will get in there and you may never see them again.
I'm using a shrimp-specific substrate as well, Ebi Gold Soil. This isn't essential I don't think, but, it has been designed to buffer the ph between 6 - 6.5, which is a nice range for most types of shrimp. It also (is supposed to) keep the water nice and clear, too - which I like the sound of.
You've already got quite a mixture of shrimp some of which can tolerate different temp ranges, but, I'd suggest a temp somewhere 19 - 23deg. When you say nano shrimp, do you just mean juvenile shrimp or is that a separate species? I have amano shrimp currently living with some Fire Reds, Black Crystals and Pure Redlines and the amano have never shown a single bit of interest in any of them...they don't even bother with their own molts.