Jelly rolls are cut 2-1/2 inches wide and length is the WOF (width of fabric) - usually between 40-42" long.
I do use them for binding sometimes, and also for sashing (strips between blocks in the body of the quilt). I use them less often for borders (which I think is what you mean by "edging"?) because I prefer one long piece of fabric for borders but I HAVE used them there and there's no reason not to.
It's cheaper to cut your own strips, but sometimes the convenience and/or variety of a jelly roll is just the ticket.
Standards for edging...not sure if you mean binding or borders? You can do with or without both of those things, as it happens.... Many modern quilts have no borders, and for binding you can do the "birther" method where you sew it together inside out and then flip it; OR you can bring your backing around to the front as sort of a false or faux binding.
Tons of options! The "right" way is the way that works. ;-)