If I go un-force-tested, and reach level 6 (or whatever level it is that the force thing resets), if I was FS before level 6, just not tested, will it reset and have a chance of me not being FS after level 6?
You are incorrect. The server calculates your FS chance, and if you do become FS, you are tagged as so in the database. Then whether you are tested immediately, or in 20 levels time, your facets will be based on the point where you were found FS. SO new levels won't reset it, and it doesn't calculate it when you are tested.