I'm glad my suggestions helped. For awhile now I've been dying to do something similar to your project right now, but due to time, I haven't anything committed.
So when it comes to Heroclix (and unfortunately I don't have any Horrorclix), take a look on the Heroclix website and if you see any you like to modify, let me know cause I should have it.
I really like the concept of Ghostbusters being incapacitated with slime tokens, that's a great touch. As for running back to the firehouse each time when capturing ghosts, its not a bad idea but I have a few ideas how it could work:
1. Instead of running all the way back, you could just take your movement turn to instantly go back to the firehouse. This way, it'll prevent the annoyance of running back and forth.
2. You could possibly have trap tokens. Each token represents one trap and you could either collect them via cards or however you'd prefer. This way, if I have 6 trap tokens, I can continue my busting rampage and then worry about dropping it off at the firehouse. It would also work in addition to the 6 spots you have on the cards.
Of course its really up to you as to your decesion, but I love the progress that this is making and when this is done, I'm looking forward to bustin' some heads,
.