Yes, exactly the CP250 fits.

Yes, CP 250 is correct. Cheap to buy at Coop Bau&Hobby (approx. 4.50 per piece).
At full load, one cartridge lasts for 24 hours. At the lowest setting, about twice that.
ATTENTION: for 230 volt operation you have to buy an adapter plug CH-EU, as only an EU plug is attached to the unit. It is a pity that this is not mentioned in the description of the appliance or that Galaxus automatically supplies the adapter plug! :)