Newb questions

Welcome to the club, the raft is a way to get delicate parts to stick better to the build platform.  Once you're dialed in there is not a lot of need for it but it helps in the beginning.  There is also support which can be enabled that can allow you to print overhangs and features that you couldn't otherwise print.  Both of these are enabled through settings in the slicing software that converts the STL file to gcode. 

Glass bed is when you add a sheet of glass to the top of the heated or unheated aluminum build platform.  Main purpose is to enable faster switching between prints so you don't have to wait for the bed to cool off and reheat to start your next print.  Added benefits are it can provide a flatter surface if you have a warped aluminum bed, and coated with hairspray many find that it's a superior sticking surface than aluminum and kapton (orange tape) that comes with the SD2.  The better the stick the less warp and curl you'll get. 

Also important is to enclose the build environment to keep a more constant temp to combat warping and curling. 

Hit up the search box and wiki.solidoodle.com for lots of information.

Thanks!