Welcome Nelson,
as above the battery pack, sometimes called Autonomy, should include a battery and the relevant charging when on hook up. Your car if set up for it should also charge the battery when on the road along with provide power to the fridge. This is not always the case on VAG cars so you may need to check.
The automatic brake adjustment is just that, as brake shoes wear an adjuster mechanism does it's job. It is not a form of stability control such as ATC.
Regarding a portable loo for your new 410, having had a portable Fiamma for our loo-less 310 I would advise getting the tallest you can store.
As a current caravan owner you will have the majority if not all of the gear you need. The only exception is probably an awning. You will know if you need one from past experiences. If you do then new Eriba fit awnings are fairly limited. A Kampa Pop-Air Pro 340 would meet your needs if you require something suitable for 2 but not a family. It is fairly quick to put up, easy/quick to take down and reasonable value new. You must however make sure you get one of the 2019 onwards models for your van.
The Isabella Shadow is a common purchase for sun protection and will take fairly heavy rain. You will need the 3m version.
Colin