The REG says abilities completed on a previous turn are CBN. Aaron's SA doesn't "complete" until he's removed from play. That doesn't mean it can be negated, just that I'm not sure as to whether or not it can be.
Like Pol said, only the placement is CBN on placed enhancements - the rest of the ongoing ability should be able to be interrupted. Again, I'm not really sure.
So the first (quoted) question is mostly due to my foggy understanding of how ongoing abilities activated in a previous phase work. If they gain CBN status, then I Am Salvation is useless except to negate LSs drawn while it's active (unless there are different rules for LSs and other cards). If they don't gain CBN status, allowing ITB to interrupt all (in battle, in territory, etc.) ongoing character/enhancement abilities could have larger consequences than desired.
The second (quoted) question was more of a real question. According to the REG, yes it should, but based on some of the arguments in this thread (emphasis on battle), ITB could wind up being restricted to only the current battle.
