That's an interesting idea, I don't know what happens if you change the abilitybonus internalname.
ABO? Don't know what that means.
You want to have three different ways of getting a trait? I don't think that's doable, although some have said that if you simply include multiple unitstat prereqs in the same abilitybonusoption it only needs one to appear. I don't know, never tried.
Yes, giving them unobtainable prereqs blocks them from appearing (but not being given out to champions in unittypes for example).
Other than that, you are entering the area where I have no answers. You'll have to try it for yourself and see how it works.