I don't use a laptop, and we don't have the luxury of a FoH person, so I have to do it all, which isn't ideal. I use an iPad, and although I use the mixing station app, I still use the X18 app in times of panic, probably because i find the layout more familiar. Certainly easier to setup the compressors etc on mixing station.
Actually I do take a laptop occasionally, I have an old macbook air that I use when I want to record stuff, generally just straight into garage band (remembering where the record enable is!).
Seeing as I also use my iPad for synths and occasional lyrics, it can get a bit multitasking some times!
Me, the singer and the drummer are in ear, the guitarist isn't.
I didn't actually use a separate wifi router for the first year of having it until I ran into trouble, its uncommon it happens, but when it does you will know about it. I just use a cheap router that is actually smaller than a mains plug.
Mine is actually the X18, as it was £100 cheaper when I originally upgraded from the XR16, although now it is the same. Functionally there isn't any difference apart from an additional phono output.
The only thing you can really do is spend time with it - some things are obvious, some things less so, especially routing of effects and effect channels, but familiarity helps with all these things. They are amazing devices, although I did a gig once with a X32 and was rather impresses with that (although not the screen!)