For all the crashing, it may be some mod you have installed
And the fire one: I have experienced this myself and I solved it. Start up the Skyrim launcher and got to options and turn anti-aliasing and anisotropic filtering OFF. Thats should work because I no longer have problems with it.
Now about my skyrim.... Whenever I play some items are missing and replaced with red triangles. They could have been chairs before, but when I try to verify integrity of game cache, it just says 1 file is missing and it will be replaced, but then I double check it and it still says its missing...