How to season/marinate/prepare/etc it?

Hot smoke or cold smoke?

For hot smoke, pretty much season it any way you like. You can do anything from a little coating of oil and salt and pepper to a mustard and dill rub. I tend to go simpler and add spices when I eat it. For cold smoking (making lox), you usually want to keep it pretty plain. For wood, I'd use a milder wood like alder, oak, or a fruit wood. I wouldn't advise hickory or mesquite as they will tend to overpower the salmon (or any fish).

For cold (sometime for hot too) you really want to cure your salmon in coarse salt. Just cover your salmon with coarse salt, (skin down, flesh exposed to salt), then put a gently pressure on it, let it sit all night in the fridge... next day rince your salmon well to remove the excess salt, and its ready to smoke.

I've done the brining to make unsmoked gravlox, but the recipe I got for lox calls for light salt. It turned out pretty well the only time I tried it. What does the heavy salting do to the smoked lox?

Gives you that ferm texture you are looking for for cold smoked salmon... also you are removing water in your salmon, its concentrating the flavors, as well as seasoning your salmon. It's also used for conservation of the smoked salmon.

depending on level maybe try cooking on a cedar plank ?