Can a dead unit...

...Be used in as the damaging unit? I ask this because I've got a damage over time thing, and if the caster dies, will the target still be damaged if the caster was the one doing the damage?

that should work just fine so long as the unit is not removed via a trigger or the decay delay.

you may pass null units or unexisting units, but this will give you no bounty\exp

Ok, that works. Just as long as the unit is damaged.