Sasami- how hard is it to maintain a tank with live plants? Have you kept the other shrimp you mentioned? Which one do you recommend?
Purple-hops- lol I know! And 3 gallons seems so random! I understand a 5 gallon, and ten gallon but 3?!
There are a handful of plants that require little to no maintenance (besides possible trimming if they start growing out of the tank or something, haha). The two I mentioned, java ferns and java moss, are examples of such plants (small anubias species, flame moss, and water sprite are others). Both can also be attached to a rock or piece of driftwood (as opposed to being planted directly into the substrate) which is a necessity with the undergravel filter (you can't keep a plant with long roots since they'll get tangled up). The other option is to use pots or ditch the filter in favor of a small hang-on-back model (which I'd probably recommend either way).
Yes, I've kept the other species. If I had to pick, I'd go with cherry shrimp. They're a bit hardier and breed readily (this means that not only will the ones you purchase be captive bred but you'll also have a steady population). Plus, they're very colorful and look especially amazing when contrasted with live plants and a dark aquarium background
. The only maintenance needed for them would be to drop in pellets as food a few times a week. Partial water changes will keep water quality consistent but you won't need to change the water as often as you would for fish.
Many people also choose to supplement Iodine. It seems to help shrimp molt. You just need a very small amount. Aquarium Iodine supplements are generally made for marine reef aquariums so you'd use half (or even less) of the dose recommended on the bottle.
The cool thing about the live plants is you won't have to deal with the ammonia and nitrite spikes common in new fish tanks. The shrimp won't even produce much waste and the plants will soak it up.