We actually started mostly using flood lights. I think we had 5 of them. Then a member (Halloweenie1 - check the photos of her haunt if you haven't - it's really beautiful) suggested we cut back because we were just washing everything out. So that's what we've been trying for, but we always end up thinking things are too dark, and putting some floods out.
Last year I mede a bunch of LED spot lights that ran off of batteries, but they weren't as bright as I hoped. And I think we still ended up using the floods as a result. We did have one gemmy LED spot and that was really nice. (Here's a pic - blue LED spot in the front, red flood on the tree behind).
Everything is still way too bright though.
So I'm hoping maybe some these Spirit spots will help and we can retire some floods.
Yeah, you're right about the purple being a blacklight. I think my store had red, blue, green and the blacklight. I would think the only thing you'd need to worry about in terms of leaving them outside until Halloween is theft. But I could be wrong.
If it fits your haunt, I think it's great to have - I think they call it "practical lighting?" Light that actually comes from your props, like lamps or candles? That seems to help.
I don't think we had ANY lighting our first year so you're off to a pretty good start. :)
Happy Friday the 13th! :) (I'm always misplacing my knife...;) )