In that case, go to (or search for) themes and change Evolution to Enhanced theme, which looks like in the old days around 2008. I'm still using it too for myself.
That will look a lot more familiar to you and then you can get used to the Evo skin on a user account for yourself or something like that.
As for creating nameservers, you do have to set them up at the server first, so NS and A records for the nameservers.
Then at the registrar, point the ns1.domain.com and ns2.domain.com to the ip's which you setup for the nameservers on your server.
I don't use nGinx, can't help you with that, but there is a lot of info in the docs indeed.
There is no itemized list for the installation as far as I know, however I still use this one with the pre-install commands:
Installation is gone a bit different nowadays, if you choose auto, all will be installed for you, newest exim and mariadb and stuff and also CSF. You can get it so you can choose things, but then you have to use command line options. There is a thread somewhere about that.
However, now DA installs directly and all the rest in the background, so you can enter the DA GUI and configure some things while the installation of all the rest is running in the background.
Bubblewrap? I wouldn't know the benefit of that when you don't give users any SSH access.