Wirelessly posted (Mozilla/2.0 (compatible; MSIE 3.02; Windows CE; PPC; 240x320) BlackBerry7290/4.1.0 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/100)
I'm a t-mobile BIS user, so I can't speak directly to some of your questions, but I think you're asking too much. It is going to take some messing around to get IM up and running. Why? Because it's a business phone at it's core, and you're asking it to do unusal things. I don't think BIS is that much worse than BES, although I do with I could do a better calendar sync. But maybe that's just cause I'm using t-mobile. Also, I'd investigate using google talk and gateways to do IM. That's what I'm using and I'm very happy with it.
If you want something that's going to do everything you listed out of the box I don't think BB is for you.
Maybe that qwerty LG thing that cingular offers?