hahaha i'm all over these AIO nano threads today, anyway.
the biocube has a decent mechanical filtration system, 3 stage wet/dry. so you're good on that, if anything get a koralia nano powerhead or something similar.
1-2lbs of LR per gallon is a rule of thumb, but you can do what you like better (as long as fish have some swimming room). live sand is also preference, 1-1.5lbs of sand, but dont buy the live stuff, its a gimmick and not worth the money they charge for it.
can't wait to see pics of this being set up!