Diablofans has an interview with Jay Wilson about Diablo III. The question about the Monk yielded some interesting tidbits such as the replacement of the Skill Tree by a brand-new skill based system the team is experimenting with. We will learn more about it through the Diablo Twitter in the near future. The female monk is nigh done, and will be announced soon.
Jay teased there are things they haven't announced yet which allow players to customize their characters' stats through their items, thus forget about the original Diablo's elixirs. A level 100 character on harder modes will have unique item / gear models not seen in easier modes -- not just a rehash of the same item-model with a different name.
Concerning immunities, my interpretation on Jay's answer is that in Diablo II certain bosses had a full immunity to a magic resistance (i.e. immune to ice damage) --- I remember back in the day when I played single player with a sorceress and focused my skill points on ice-based spells ... let's just say, it wasn't fun fighting Duriel and running like a sissy. Apparently, in Diablo III bosses won't have the same problem. You might have other spells or abilities that you usually don't use much to adapt to every situation. Bosses will still have a certain degree of resistances, but nothing so extreme as in Diablo II where you could be stuck, or forced to play in a group.
Unique items are known in Diablo III as Legendary Items. Vendor NPCs will still be there to offer weapons and armor to fill the gap on the random / luck drop factor. If you haven't found a replacement for your boots, you can simply buy an item from a vendor while you find something better to replace it with.
The biggest turn off of the interview was their decision to not include Ureh in the first installment of Diablo III to save time in their internal scheduled development. Thus, Ureh is likely getting some development-time in future Diablo III expansions. PvP was completely ignored with no comments.
Female Monk animations nigh completed
Skill Tree replaced by Skill-based System (no more Wow/Dii Skill Tree)
Twitter will be an exclusive source of Diablo III news
Unannounced Stats customization through items
Difficulty Mode at lvl 100 gives items/models not seen in easier modes
No more full resistance immunity bosses or rather unable to beat them. Keyword: Adapt.
Ureh won't make it into Diablo III