Jason Hall , Sep 26, 2008; 11:54 a.m.
The sensor cleaning, I am sure does help, but does not take care of it 100%. So you will still need to clean it from time to time. Just maybe a little less often.
Bulb, as with any EOS camera, it will keep the shutter open until the (shutter)button is released, or the battery dies. There is no time limit. Any Canon DSLR can be set for up to 30 seconds exposure, but that is not "Blulb".