Bear with me and I will link you to some simple plants that will grow in any lighted tank.
Guppies do not school so 3 is fine. There may be an occasional bit of chasing goes on but nothing dramatic and with plants all the fish will have somewhere to hide when they feel the need. There is another valid reason for having only male guppies by the way, they are smaller than the girls so they have less of a bioload on the tank.
I am not a shrimp expert Alyeska has recommended armano and i would not doubt her, ghost shrimps & cherry shrimps are possible alternatives
I was diplomatic and tried to ignore the snail lol to me they are pests. BUT that is only my opinion.
Zebras are a no, they need to be in groups of 6 or mor eand you do not have a big enough tank either in term of gallons or more importantly swim room
Plants
Amongst other I use this site
http://www.practicalfishkeeping.co.u...section=plants to give me ideas on plants and
aquascaping ideas. Please though do not start to worry about CO2 injection systems in your tank if you stick t simple plants like Java Fern, Java Moss, hygrophila and Anubias