I can't see the harm in trawling through legends mode, and I've been giving some thought to the possibility of playing one of the other modes as well. Just seems a bit cruel otherwise.
Adventure mode, however, apparently offers a remote chance for finding and checking out some of the new, ah, "features" firsthand. And arena mode lets you figure out some of the quirks with combat nowadays, as well as providing you with details on some of the enemies we'll face (like, for example, the fact that iron men are far, FAR more dangerous than they ever were before).
But still, the on-the-level details of fighting won't give you *that* much of a leg-up as far as fortress building/management is concerned. So, since y'all asked nicely and brought it up, I'm gonna have to give the okay for playing arena mode as much as your little hearts desire. Besides, there's still plenty of other stuff that can't be spawned in the arena, so it doesn't exactly remove *all* the mystery... Heh heh.
DFNewb, I'd be happy to have you on board, but I'm still going to have to give the others preferential status as far as placement is concerned, and I haven't heard anything from Katsuun or Paulus Fahlstrom yet. It's just that they've agreed ahead of time, y'know... I can put you ahead of other newcomers though, since you lack experience with Fort mode.
Also, I need to update the OP with more slots... It's not like there are only ten places, it's just that I only made up ten to start with.