The falling leaves actually use up just very little of the performance. I tried it already, did not notice any performance difference and decided to leave them in both settings.
I don't know if the ABS resembles so much of Chain of Memories. I played that one like 5-6 years ago. Charging weapons is a part of several Action Based Games (Secret of Mana for instance), the difference with mine is that the weapon changes every second. :)
It is by the way not random. They return in the exact same sequence. If you know that the Healing spell comes up every 5 times it will come back in 5, 10, 15 times and so on.
I would consider my level up system as a mix between FFX and FFXII. ;)