I really hope Omar Doom, Eli Roth, or any of QT's other mates - who bring fuck all to a film if not serve to weaken it - aren't in Django Unchained. For me, the integrity of IB (and DP) was tarnished by having jokers like those two in them. It did used to be the case that QT chose the RIGHT actors for the right roles, but after DP and IB, it's just not the complete case anymore.
Also, I'm a bit sceptical of people's reviews of the script at the moment. I remember when the script for IB leaked, and there were some rave reviews about it, with QT apparently back on form with his trademark dialogue. However, it ended up being the least Tarantinoesque dialogue I've ever heard. I'm not saying it wasn't good, it just wasn't classic QT in terms of word play and wit. It was mostly serious in tone. I thought KB's dialogue was vastly superior anyhow. Even QT said it was the greatest thing he'd ever written, but I thought it was far from it.
IB was a disappointment, albeit not a huge one, but I did feel underwhelmed nonetheless. It WASN'T "the masterpiece" it was hyped to be. It actually felt like a poor man's Kill Bill. With that said, I do not have any sort of expectation from Django Unchained. I would be doing myself a disservice. Therefore, I won't be reading the script (maybe the occasional bits of dialogue), and my excitement will be muted.
The news about Will Smith isn't really a surprise. I think he's doing the same thing he did with Pitt in IB.