Wedge for Astrophotography

[pmaguire]

I'm new to Astrophotography. I have just upgraded from a completely manual
6.25 inch Dobsonian to a Celestron Nexstar 8se. In order to do photography
I bought the optional wedge but I am having some difficulty understanding
the setup.

I have a few questions that are not clear in the manual. For reference the
wedge is http://www.celestron.com/c2/product.php?CatID=13&ProdID=381

What does the Azimuth Adjustment knob do, how does it work?

The manual says "Position the telescope tripod so that tilt plate hinge is
facing towards north", as the wedge appears to have a swivel on each side
rather than hinge running along the width, How am I to know when is facing
exactly North?

Similarly when aligning the tube using the hand control in EQ North
Alignment mode, one of the steps is to find the Meridian. Aside from
assuming the Meridian referred to is the imaginary line running from Pole to
Pole directly above my head, how do I know when the telescope has actually
found it?

Patrick