Some things I do not like.

[Absimiliard]

You might be able to save yourself some trouble by picking up a gaming mouse. You can assign the keys on a gaming mouse as substitutes for shift and control, and depending on model, it may be within the range of motion your fingers can tolerate. Even a cheap one with two or three extra buttons can make a world of difference. I don't foresee the devs adjusting the number of abilities in the near future, but this one small change might go a long way toward making jobs other than summoner approachable for you. It would probably make summoner a tad bit easier as well.

And don't worry too much about flowcharts and all that garbage. That's really only useful if you're going hardcore. For the average player, avoiding dropping your combos and using your cooldowns/off gcd abilities as they come available will do just fine.