Drift wood can some times soak up all sorts of things, to be safe I would get some new wood. As far as plants go, I know that a soak for a day or two (in plain water) and then letting them in the tank with carbon for a two weeks you will be fine. If you for some reason super worried bad things still remain a few ghost shrimp for a few days will be a good indicator.
You never know sometimes great things come from ashes! Keep moving forward!