Welcome to the world of planted aquariums, let's dive right in and see what we can do for you.
Air pump - no need since plants use Co2 and then produce the oxygen in the tank.
Filter - I'd go with the Red Sea nano filter, since the flow rate of it won't destroy the substrate, and plants.
As for gravel, you'll need to use root tabs under the gravel for the plants.
45g Long - High Light Planted Tank / 30g - Plant Grow Out Tank / 100g Tank - currently resealing