A micro-setup is a good idea, a good way to familiarize yourself without spending a fortune .....please keep us up-to-date on your progress
Just keep the 2:1 or 3:1 ratio in mind for the GB to FT and you should be OK as far as bio-filtration...... They sell micro-hydroponics in the local hardware store that only hold about a 1/2 gallon of water, so I think the 3 gallon would be fine for your experimenting. I would suggest a better pump tho, as you want to 'change/recycle' the water at least 3 times per hour That would mean about 10GPH for your pump at whatever height you may need.