Mystery Script Help, cause I need it. >.<

Since verbs are a bit advanced, due to the way BYOND is set up (doesn't let you make real verbs at runtime so I had to work around that), I suggest you make Doppelganger mode (Advanced Tutorial) before getting into things like that. Second, apologies that there aren't more guides available right now (I'm working on it), but you should be able to infer what each function does by going to the Features, Functions, and Variables thread. The second question is kind of touched on in Doppelganger mode as well, but it is a hidden overlay instead. set_icon will do what you want, once you know where to put it. As for a projectile, the create functions will do what you want, so long as you program the behavior for the projectile. If you are an artist and not a programmer, I suggest you wait for the Mystery GUI or take up some programming in other languages before going onto Mystery Script. There you can find more guides on basic programming, which will help you with Mystery Script as well, while the Mystery GUI is more like RPG Maker where you basically click to make events happen. This will be catered to the general audience rather than just programmers, but again, I've been busy, especially with Kosei Online, so development for it has been slowed.

It's more efficient these days to put those into functions and just call the function for the verb, instead of a separate file. Other than that, good job, even though shooting doesn't really call for spawning an entire weapon, just an object. I guess since native loops can be faster than MS loops, it may be a better idea, now that I think about it. Just initialization would be slower, though, so it depends on how long the fireball is out to see if it is worth it.

Also, for the icon portion, it's just like the invisibility code, except that you'll need to store the player icon somewhere globally, like an MSTag, and then use set_icon instead of invisibility to switch between your custom icon and the normal icon.