Arch Linux keeps up to date always using the latest available version of the kernel
Can i3 be installed on a fresh Arch Linux ARM install without any additional software packages?
For i3 to work on a fresh Arch Linux install it requires display packages, a dynamic menu package, and a terminal emulator at a minimum
Neovim is only one choice out of many that can be used to develop on the Pinebook Pro, and it really comes down to personal preference