Here in the forum it is mostly just user to user, so for TOTALLY solid answers on some of that you're probably going to want to ask support directly through the panel.
I am not a podcaster... yet, but I have thought it out some. As near as I can tell, unlike Libsyn, who is 100% a podcast host, with lots of podcasting needs preset up for you and somewhat automated (the iTunes integration, for instance... despite it not working), at Dreamhost, from what I can tell you'd pretty much be on your own with the iTunes stuff, BUT iTunes would have a way for you to handle publishing to them manually... you would want to go to iTunes and see what kind of code they offer for manual integration into things (for instance, there may be some sort of WordPress or Drupal podcasting pluggin that auto updates iTunes for you if you have your iTunes code to input or whatever).
I would imagine that as long as the server is able to handle your traffic, CPU wise, you'd have about all the bandwidth and storage you'd need for quite some while!
I think you should find out every functionality that your going to want to be enabled to enjoy, be it the iTunes publishing, RSS publishing, Perhaps even newsletter publishing to go along with your regular podcast listeners (which Dreamhost has a setup for), see what will need to be handled manually, and see what Dreamhost can handle "automatically", then decide if that's doable for your needs.
"Whenever you find yourself on the side of the majority, it's time to pause and reflect." - Mark Twain