You can do some reading and learning on there and purchase there if you'd like. Check out some threads on the sales forums for dry fert sales too, prices are comparable(or cheaper!) and its nice to help a fellow hobbyist.
You can still use EI dosing on a non co2 tank, you just need to adjust based on your plant mass, lighting, etc.
Personally I prefer to mix the ferts into liquid form and dose with a syringe. You will need a gram scale for that though(they can be cheap).
Basically it depends on what your routine is. I use the pps-pro method(mixed dry ferts into liquid form) and dose every morning before the lights come on(its a high tech tank w/ co2). On my low tech tanks I just dose once a week after the water change(using the same mixed ferts).
Don't worry once you get it down its not as complicated as it seems!
The primary macro elements consists of Nitrate (found in KNO3), Phosphate (found in KH2PO4), and Potassium (found in both of these compounds as K). The other primary class of elements is lumped in what is known as micro elements which is a mixture of different minerals i.e. iron, magnesium, boron, etc."