If your tank and you are new at this then they gave you that A and B for a reason; most new people dont test their water. That A and B is calcium and ph buffer, so if you stop using it then you really need to be testing. These guys are assuming you mix your own water, but if you buy it, like lots of new poeple do, then you may not know what the salt mix is. If you buy your water you need to ask what they use for the mix, ie; the brand and type.
Not all of those products are snake oil, but it is confusing and a bit redundant. I watch what they do at the stores, the ones with a healthy reef. You need to add calcuim, and other minerals to the water once you add corals to your system, and when you're new, you need to test for Calcium, and Magnesium and dose to maintain certain levels. After a few weeks of testing, and dosing, you get a "feel" for what your tank needs. I can walk over and pour in Magnesium to tank, once a week, and not check the Mg. at all, why? After 2 yrs. of doing it, I know, half a paper coffee cup a week is what my tank uses, and I will test the Mg. about once a month now just to see, it's the same pretty much.
As you advance in this hobby you'll gravitate towards what you like, I like cool colored stuff, zoas, sps are cool, and Duncans I like, sps needs and established tank, like a yr old to be ok. You can start with stuff like zoas and hammer, leathers. You will need a good light if you want sps and some other lps.
But you need to test your water parameters and get stable, calcium, magnesium, salinity, ph, and temperature.
You need to be careful with your 10g tank, it will react very quickly to what you dose with.
I dose with Koral Color, wich has trace elements, and also Fuel, which is a food for corals with fatty acids, but thats a food, not a water element. If you want zoanthids, they seem to like Mg, so get a test kit for that.