The 1000 DTL was a very interesting camera, I had my dad's spotmatic and a friend had the DTL1000.
We used to swap lenses among them and get excellent results.

Spot metering means that the camera reads the light in a very small area of the picutre (thus a spot) and allows you to expose for such partiucular spot.
Average metering measn that the camera reads the light in the whole scene and gives you an avergae reading (normally with rpeference for the center of the image) of the image.