Moving windows around on GNU/Linux is not very smooth between different screens, at least in my experience. I am sure with enough time spent on a configurable WM, it would be great, but no need to do that with an ultrawide.
Depends on the UI you use. Gnome and tiling window managers should do it just fine. I prefer the macOS keybinds (including where full screen becomes a new desktop, combined with the "Magic Touchpad" gestures).
With regards to keybindings, one thing you can do is get ctrl/meta/alt in the same order as your Mac. Personally, I've swapped ctrl and meta on my MBP while I am using VirtualBox (with Kali) because that way when I'm in the VM I get local consistency. I usually SSH into the Kali machine from the MBP anyway.