There's a very good guide to using GPS, called Cockpit GPS, produced by a Delta airlines captain, John Bell. I can't recommend it highly enough for getting on top of all the basic concepts. You can find the PDF download at:
Cockpit and Small Boat GPS
The 495 is a great piece of kit. Have fun !
NB - wherever he makes reference to WAAS then you need to know (if you don't already) that in Europe we are rolling out (slowly) the EGNOS equivalent (i.e compatible) system. More details can be found at:
ESA - Navigation - The present - EGNOS