mine had a little plastic surround that fitted over the front around the radio , when i fitted the new stereo ( i still have the original import one if anyone wants it ) it just slotted over the front , was a perfect fit
Yep as said the brackets unscrew from the original head unit and then its a case of ditching the cage and screwing the brackets on to the new head unit as said already beware of the inards of the stereo i had to cut mine down abit to prevent any damage on the pioneer unit that i fitted.