Lowest and Highest EV value to bet on?

Whats the lowest and highest EV value to bet on?

How much does it affect the results to go to low?

Whats the max EV to go for without getting flagged?

You will get flagged sooner or later.
Higher EV is better but if you go too high you will reduce the amount of bets significantly.
Where those limits are is different between the members. The default settings are pretty good.