Mold will grow in any damp enviroment. Look in a fiberglass insulated wall in a cavity with an outlet & you will find it there too.
As far as burning, it in part depends on the manufacturer & what chemicals are used. If you have a good problem, it's not a problem. In fact, I had a insurance inspector tel me he has seen several houses saved because of cellulose because a fire will not easily pass though it.