I have not used the A and B. I use the Terra Vega/Terra Flora stuff. Do some looking around for some info. on the A/B series. You'll find it. I have found these nutrients to be effective (so far) and pretty forgiving. I'm growing in CoCo with perlite. I'm a small hobby grower.
Smaller pots allow for an easier time when trying to fill to the top. You'll see a lot of discussion on sizes of container and size of the plant to go into it.
from China???? I wouldn't eat, smoke, inhale, store, pretty much put anything from China into my body on purpose. Pesticide law says - first and foremost - that the label is the LAW. If you can't read the label you shouldn't use the product