Oh, the "system to attach to shot" thing: It goes in the system itself, actually. That's why it doesnt work, and it's why some of the bosses dont use the vars or patterns file whatsoever, because they're just able to attach systems to shots within the systems file alone.
However, if the system you're using this on has a bullet pattern of it's own, it will override this. The bullets it fires, the systems attached to them can have patterns.
That's how Palisade works, yes (some of it)? I just messed up my implementation. It's cool though since I have something that works.
Speaking of which... I had to drop the rate of fire to 1. Anything faster than about .6 starts to hit frame rate to much. And playing around with it, I think the attachments are hilariously OP. It makes trying to keep a balanced progression to this thing very hard. I'm seriously considering locking in one of the passive systems as an attachment and controlling growth through a better leveling scheme.