Installation is pretty straight forward. I don’t know if you can do much of that on install except for checking sys-whonix will be setup.
Post install, what you’ll want to do is when you make a deb or fed qube, set the network provider (which is on the screen in the GUI for making a qube (It’s the forth option and says “Networking”) to your VPN. And whenever making a whonix work station, set Network to sys-whonix.
As for saving your wifi, there are two options depending on what you want from your sys qubes. You can go with an actual appqube or you can have disposables (from the install menu or later on). If you want a static sys-net, all you need to do is type in the password and it should save it.
If you want to go with a disposable sys-net, then it’s a bit more complicated but arguably more secure from some attacks. If you want to do that, there’s some reading to do and I would recommend going in once everything’s set up and immediately make a separate template (by copying either the debian-11 or fedora-37 template) and making that the one you use for your sys-qubes. It’s not that hard to do.
Then the next piece is to make a new disposable template (based on the template you just made) to then use for your sys-qubes. disposable templates are actually appqubes based on a template. So there’s two steps to this. How to make a disposable template is here: Disposable customization | Qubes OS
None the less, once you have done that, or opted not to and will just use the pre-installed template and disposable template for your sys-qubes, you’ll want to go into that template (another reason to make the sys-qube templeate seperate, since all your other app qubes are based on the standard template. If any of those get compromised, the data you put in for your WiFi can be gathered by the attacker. But with a separate template, that’s not an issue).
A couple of ways to get it to remember the WiFi are talked about here: [qubes-users] Disposable sys-net >> wifi login