So I have my team in place and am liking how it is playing but my question is if i use a stat modifier move as in fake tears does that stat mod go away if the pokemon is called to the bench?
Stat changes, boosts or decreases, are removed by Haze, getting hit by Clear Smog, or being forced out of the active position. So yes, it does. Stat decreases will also be removed automatically the first time by a White Herb, and only stat decreases. Stat boosts will not be affected by a White Herb.
Baton Pass will "transfer" any stat boost such as Swords Dance to your own in-coming Pokemon on the switch in/out. If you use say for example Tail Whip on your opponents Pokemon, and they do not switch out- the effect will remain. If your hit by Tail Whip, and switch out- the effect will be removed.
For each level, a stat is boosted by about 1.5. So it's 1.5, 2, 2.5, 3, 3.5, 4. Accuracy and evasion increases/decreases may be different, but I'm not sure.