I'm not sure what conference you're referring to (the B1g Ten I guess), but back in the eight-team era the ACC got six teams in (75%) on several occasions. I think the Big Eight did it a couple times too. So not unheard of. Also there are 38 at-large bids now. When NC State is seriously discussed as a tournament candidate you know there are LOTS of bids out there.
Regarding the #1 seeds, I don't think we're good enough to play our way into one, but it's not out of the question. Ky and the Cuse aren't moving off their perches, but the other two #1s are certainly up for grabs. Mizzou's gonna win out? Really? In 2010 we weren't a serious candidate for a #1 until the last week of the season, a stretch in which we dropped a game even. Weird stuff happens towards the ends of regular seasons; schedules tighten up and teams start dropping games. Duke has not been immune to this phenomenon (1997, 2008).