Kia Picanto Purchase

Dear forum participants, I urgently need your advice and help with a Kia Picanto purchase. 1) Consumption of petrol – diesel one can assume that the diesel is approximately 4.5 l on average and the petroler is 5.5 l (spritmonitor). What experiences have you made? 2) Will the Kia Picanto crdi be delivered with a particle filter, which is also tax recognized? How much do I pay for taxes? 3) What is a good price for a Picanto EX, metallic ? 4) Is the term “day registration” a disadvantage? what do I mean by a storage vehicle? 5) Are the Internet intermediaries serious? What do you have to pay attention to? I would be very happy about answers!