Okay, so I wanna try playing a ghost, but I need a couple things cleared up:
-Being a ghost, and "see through and dead-looking," can I vanish in between fight scenes? I mean, ghosts can typically turn invisible in movies. Or could I wear consealing garments?
-Ghosts have access to abilities, like mimicry and mind drain, that require a "close combat creature attack" to be done. Ghosts however, do not have any access to any close combat creature powers. Why is this? Would I just make an "unarmed" attack using my creature power score?
-For insubstantial it says to choose two types of matter you can't pass through. This is vague. One could say "platinum forged by a Spanish speaking man" or be less specific and say "iron" or a cruel ST could simply say "wood" Which would render the schtick extremely useless.
Hmmm, I don't have the errata page handy so I don't know if that's been fixed already or not. Those are actually the only two where it matters, so I would just allow the ghost to use their primary AV of 13 to attack with them (but at close range, not blast range).
Yes you have to work it out with the GM. He probably won't allow your first suggestion. I think in terms of 'how general are we talking here' its supposed to be more like your second one. Wood, paper, stone, water, iron, copper, silver, salt, etc... You could go traditional and look up old ghost stories and see what sort of things are supposed to stymie them (silver? salt?), or you could go with "I'm from the ancient juncture, technology interferes with me" and pick steel and plastic, or, well heck pick any other theme for your ghost you can think of and use that to determine your substances. "Some middle eastern dude trapped me in a bottle for 1,000 years...now I fear glass. And silk."
FS2 doesn't do invisibility well, FS1 had "Blindspot" (Thorns of the Lotus) and "Invisibility" (in one of the last books published, I forget the name). The result of updating them might be a character that is effectively sneakier than a ninja, so the GM could understandably not allow it.
I have a ghost who I've given Invisibility too in my current game. Basically Once a scene become invisible until you attack (worksnicely with the Ghost's boosting stuff) use Creature Powers for Intrusion rolls (sneaking only).