Lightest kerb weight is 780kg for a 3door with minimum equipment. But I'm not sure what this includes. In Denmark we use a standard of saying dry weight+120kg is kerb. However, EU standards says car with fluids etc +75kg = kerb. And all are listed as 800kg. Every car also comes with a full size spare tyre. 13-14kg.
The water pump is the same as many other cars with bigger engine the gesring of the pulley migjt be different. The alternator is 80amp I believe, so not far off bigger/golf class cars.
Waterpump is about 2500DKKR/400$/350€
I can post some figures later, in the meantime heres a 107 which basically is the same car, making 92hp. With intake/exhaust and a tune.
https://youtu.be/8Cc3xOsWyCY
Another I know of made 95hp with stock manifold/cat. The dyno might be optimistic, but it showed a difference in 12hp before/after.
The stock intake drop to 96-97kpa starting from 3500rpm. A filter will let it up to 100-101kpa. A little science will say 3-4hp depending on how low you can drop the temperature. A bolt on 42mm ID exhaust pipe will get i 6hp in peak rpm. I had this same exhaust, wich made the same difference ad stated in the video.
https://youtu.be/gVh3rjV5Spg