How soon after the differential problem did the ABS light come on? I don't see anything related to the differential seizing that would cause the light to come on, but it's possible that whoever replaced the differential could have screwed up some of the wiring which could cause the light to come on.

However, that shouldn't cause the low fuel or low washer fluid lights to come on. Assuming that the dealer was smart enough to verify that the fluids weren't low, then a short in the instrument panel wiring could be a likely cause. If they fried your computer while attempting a repair, then they should be responsible for locating and installing a replacement.