Regarding your 2nd point, yes, Sonar uses Letters to identify busses, but there's also a Name strip which you can double click to over-type with your own descriptions.
I find the easiest way to insert busses is in Console View (Views-----> Console View)
Scroll to the right hand side of the screen, there you will see your Main Outs (Some people call these their Soundcard or Interface Outs). To the left of these are your busses. Right Click in the grey space between existing busses & mains and choose "Insert New Stereo Buss"
Now you can route any (audio) tracks you like to this buss