alright basically its like this:
1) Schooling fish are anything species that prefers/almost Needs to be with a group of the same fish. These are generally called community fish but other "semi-aggressive" do as well. just ask someone. Average price per fish i'd say around 2.50 but can range between $1-$15
2) A Planted tank is a tank that well.... is planted. this generally means buying special substrate (the ground stuff ie gravel, sand etc) and laying with small ground covering plants over the whole thing. Let those grow out a little bit and and add more bigger plants. Can be costly and time consuming but looks great and is very clean
3) A Filter for your size tank would average somewhere between $30-$90 depending on brand and type. there are many types of filters just ask about some but more populars are canister, wet/dry (aka waterfall) and powerheads.
.... just ask more this is just an extremely basic synopsis as i am NOT an expert by any means