bottom feeding is better for something that doesn't require fertilization - a living or super soil type medium would be best.
otherwise you have to worry about buidlup of nutrients in the medium over time, which you can mitigate with some top-down hand-watering in some incremental way.. how often will require some trial and error... wait to see some tox signs and you know you have to do it well before that point in future.
if fertilizing through bottom feeding, just make sure it's not seaping through tiny orifices... e.g. those "Blumats" would clog up over time much faster than with plain water.
topping an autoflower isn't too useful, but as long as you don't cut off too much it doesn't hurt you too much, either. Even so, i'd stick to LST with autos.
'mainlining' or wahtever.. just don't strip all the leaves off, that's retarded. training is training regardless of the silly names people have come up with. manipulate apical dominance and get the shape you want.. nothing more or less is needed.