Whether it is right or wrong, I don't know, but I have always felt I was supposed to leave Master at 0 unless fading out (or in). I guess this comes from working on multi-track tape machines and analog consoles that are tweaked so that 0 on the console is 0 on the multi-track tape machine which is zero on the 2-track master. For that reason, if a mix is overal 1 db too loud (for example), I adjust all the other buses that feed Master slightly until I have the level right and I leave Master locked on 0.
1-If it is OK to change Master (and I don't know of a reason that it wouldn't be), it would be a lot easier just to make a slight adjustment there to get the peak level where I want it.
2-If not OK to mess with Master, then the super-bus is a good idea for that.
For the record, I normally send everything to a bus (Vocals, Harmonies, Guitars, Keyboards, Strings, etc.). Even if there is just one instrument in a category (like Bass), I still create a bus. My thought is that once I have all the fader movements set, I can easily adjust the overall level at the bus. (This prevents me from having to use the dreaded Offset function.)