I am pretty damn sure I have made food/elixirs that has three different descriptions of protections on them. However the medium protection and high protection both ony have two snow flakes next too it.
As for Fireproof, I think you can still make them level 2 but it requires 4 smothering...
There are two levels I think. One gives normal fireproof and another gives high. Really wish they just made it Heat resistance instead. Cold and Heat to my knowledge has THREE levels attached to it.