Regarding the length issue, I think that when a band is set on filling up a CD, what often happens is that they end up with a lot of... well, filler. Fluff. Tracks which don't necessarily match up to the others in terms of quality, but which are included anyway for the sake of having a longer album.
I'm overgeneralizing, of course. It's possible to have a 78 minute album of all-killer-no-filler. But when it comes right down to it, I think a shorter album is a pretty good sign that the band is being more selective about what makes the cut.
Incidentally, I've made this point before, but last time I made it, I was discussing a 40 minute album. Now I'm discussing a ~70 minute album. Only on DTF.