Seat Leon 2.0tdi 150ps new or used? Some questions

Hello guys, my old car is now more of a construction site. That’s why I want to get rid of it quickly for a 1000s. So I created the new Seat Leon FR 5-door, which makes a solid impression for me and seems to be quite good in the area of “price performance”. My goal is generally to finance the car 3-4 years, then to drive still 3 years (10 years and 200t km should already create today’s vehicles). That’s why I tend more to the diesel. I drive so about 1 5-20t km a year. Euro6 should the Diesel Leons all have? Question 1: Is there a number for the tdi from which year of construction one can easily buy. I assume that the first Leons from 2013 should still have some standard problems, which were improved in the course of the years? Engine etc. Question 2: Did the Leon Diesel all Euro6? I have read some different things on the Internet. However, do not want a Euro5 car anymore due to the problems with diesel tax/A bgaskram etc. Question3: If I see it this way you get the Facelift with full equipment for 22000 Euro. Well equipped used from 2014 but also for hardly less than 15-16000. Do you think it is worth taking the risks at all for the used or would be a new, as first owner with 3year guarantee not the better alternative in terms of durability and possible resale price (+ anyway 3 years no problems due to the warranty)