Adjusting Shocks front and rear

Hi Chaps

One of the Gents I rode with a few weeks back suggested taking a screw driver to the top of the adjuster on the front forks, i think he mentioned this was the air bleed screw, and should be done every now and then. How does one do this, sorry i clearly was not paying attention.

Secondly, the rear shock seems to have loads of setting on it, is it possible to lower the rear at all by adjusting this shock, im short and this bike is tall?

Thanks guys
Jayson