Volvo V50 brake rear axle and diesel additive change?

Vehicle: Volvo V50 Type: 1.6 Diesel / 9101 / ABO EZL: 06.07 Moin you experts, I would like to change the brakes on my rear axle with a friend (the car’s tail has) and I would like to fill up the diesel additive. I have to bring the parts with me. Now I have already picked out the parts. Once a set at ATP (https://www.atp-autoteile.de/…/details) and the parts individually at (https://www.kfzteile24.de) disk (https://www.kfzteile24.de/index.cgi?…) blocks (https://www.kfzteile24.de/index.cgi?…) Are the parts so far right? Do I need anything else? Small parts? Can you recommend these shops? Or do you have a better one? To the diesel additive, I would like to know if you can fill it up on your own or if you have to answer to the friendly one? If I don’t get the right greeting for Alex?