Looks good so far!
What kind of Shrimp are you thinking?
My faves are:
Black Bees [I think...]
Ghost...and I think that's it! lol... good luck on your tank and I hope it progresses well!
As for a light...a regualar 15W T8 fixture will do ok! They are made in 20"...but, if push comes to shove you can always search on the web for one...a better one or even thaat one. I have trouble finding lights myself and even more trouble convincing my parents I need them!...too bad it's my money! Well, off to work in a bit!