The terrarium should look great, I have been thinking about starting one myself.
As far as filters go you don't really need to buy a canister unless you really want to. I use AquaClear 20s on all my tanks of 10 gallons or less. I prefer them over canisters for nanos as they are easier to clean and easier to adjust the flow if necessary. And they're a lot cheaper, around $25 for an AquaClear 20 as opposed to $80 for an Eheim 2211. Just my two cents