The briefing of the mission alerts for the fact that you should be prepared for piercing damage, but it indicates to use [b]freeze[/b] resistant gear, that I belive should be fire resistant indeed.
For the second stage, there was no kind of great boss, all the journey looked pretty much like 2 random stages at an elevator (I was looling for a Toxilargo -like boss from the Oilers, would be fun).
Sorry, I mistook the missions descriptions. My bad.