To calculate the needed value, enter your desired framerate here.
Now take that value you got and append it to 0.0. For example, for 60FPS, you would enter 0.0167, and press OK. If it didn't work try changing more values.
Note: Screen shake amount is dependent on framerate, presumably due to spaghetti code.
The best advice I can give you without sending you to a long series of tutorial vids and a super long tutorial thread is to tell you to play with a ...
...which is a bit of a clickbait title, but as far as I know, people usually point to Caernarvon as the best tier 8 heavy and, in my opinion, T32 is ...