Purchase advice

Hello forengemeinde, at the moment I am about to buy a new car. Since I prefer Audi it was clear to me that it would become an Audi! I fluctuated between the A5 Sportback and the A7 Sportback, but later on. 1. I fluctuated between the Audi A7 engines 2.8 FSI (204 hp) and 3.0 TFSI (310 hp) both V6 engines. Therefore, my first question. Do you notice the more than 100 hp difference? If yes, when. Do the 204 hp also have neat fuss, so that you can get it in the vehicle as with the A4 Av with 272 hp? Do you need the 310 hp or do you already have 204 hp? 2. Is a row 4 cylinder petrol engine always better than a V6 engine? 3. Where is a difference between the A5 SB and the A7 SB, next to the other class, weight. The length is only very low, it is only 20 cm, right? Which would you take? Advantages and disadvantages, please.