Answers to those questions:
It's actually 29,825 kWh in a year. 81.71 kWh per day and yes, it does seem a lot.
Calorific value is 39.0
It's an analogue meter, imperial measurment ft/3 - they are billing us against ft/3, checked that already.
1 unit is 1 cubic ft.
The boiler is a...