They dont squeal, they make a grinding noise on the slots. I have a set of DBA4000's and RB74's and if you brake heavily, they will make a grinding noise as the slot "cuts" into them. I dont know how much dust Ultimates throw, but I cleaned the car yesterday, did a bit of "spirited" braking last night, and the front wheels are covered in dust again... maybe I just notice it more because theyre white.
Dont let the above things scare you though, they are an -awesome- pad and I wouldnt run anything else anymore. Small sacrifice to pay (with noise and dust) for the shitloads extra performance they have over the EBC Greenstuff that was in there.
EDIT: Oh also with regards to fade, if youre running a good brake fluid then the hotter you get the brakes, the better they keep working.