DA ED IF SDM are abbreviations used by different lens maker to mark the capability, lens build, control motors etc of that particular piece of glass. IF - internal focusing, ED refers to glass type and treatment / coating that adds to the final quality of the image, color reproduction and maybe flare control. Equivalent of image stabilising we have OS or VR. Silent AF motor with USM from Canon and HSM from Sigma for example.
Fixed focal lens = prime lens (inevitably better image quality with less lens elements)
Big aperture that can be forced to remain fixed throughout the entire zoom range (if this number appears in a zoom/ prime lens) = fast lens. Not because it has a big aperture but due to the big constant aperture thus alowing any desired shutter speed or the fastest shutter speed to freeze motion within having to sacrifice brightness or sharpness of a photo.
went to tried canon eos 1000d...first time using dslr(only use slr before...a very very old model)....and was quite impress with it.....but is only from LCD...at least the pics turn out to be what i expected after i change the setting(shutter speed,aperture,iso....playing around)....