How does it not work exactly? It might just be a matter of tuning the numbers a bit; I think the idea is sound.
I think shootval gets reset once a shot is fired, so you'll need to reset it every time, yeah.
There isn't a great way to commit suicide, on purpose, since it could be a really good weapon. Your best bet is probably to fire nrg shots and build venom and poison and body to exhaust the nrg supplies.