Just made grilled cedar plank salmon, living where both wild salmon and western redcedar (Thuja plicata) are still somewhat plentiful if not available for now, so:

1. have had at least 2 uses out of the planks. Then again I do soak them for at least 8-12 hours. Looking at the planks I used last night, I think may be good for a 3rd go, if not a bit charred underneath.

2. Yes, they clean up well. just scrub them off.

3. The flavour you're aiming for it thujones, the aromatic chemical found in Thuja spp and reportedly also what you find in absinthe. No smokiness unless you burned the board. It is more of a dry steaming process.

I find that reusing the board results in less Thujoney flavorful fish each time so if you want to full effect, use new wood. What you can also do is soak the boards in as little water as you can so the thujones aren't diluted away (you see the water becoming dark as it is leached out).

5. Never tried it with charcoal/coal dust. Just gas.

6. Don't buy planks. Buy untreated cedar fence board (lot cheaper -$3 for a 4' long 6" wide fence board here) instead and look for the dark rich red colour of the heartwood, not the white sapwood. You should be able to smell the thujones.

I don't oil the fish but put the fillet skin side down. Not need for it as the (pacific) salmon is plenty oily.