RE: Cedar plank salmon
You can do other fish besides salmon this way. Trout is often grilled on a plank. You should soak the plank for about an hour, and you can use a gas grill. Make certain, though, that any plank you use has never been treated in anyway. Here is one place you can order cedar and alder planks and be sure you are getting untreated wood:
By the way, there's an old shad recipe in which you nail a shad to a plank and grill it till the shad starts pulling away from the nails. Then you throw away the shad and eat the plank.