1) There are another 4 recongized Ubuntu spins for KDE, Gnome, LXDE, and XFCE, plus all the derivatives with other desktops like Cinnamon, Elementary, Enlightenment, and Zorin. You are not limited to Ubuntu Unity, and unlike any other OS you do have options.
2) I haven't had that much experience with Windows 8, but for many systems the UEFI implementation by the vendor is so bad that it will only boot singular binaries in the Windows EFI locations. That means you can never have multiple OSes on that EFI, and there ain't jack any Linux distro can do to change that. Additionally, Windows will wipe all other EFI applications when you install it and it regenerates an EFI partition, as it always has in every version ever, it will never play nice with any other OS.
3) This relates to 2, but if hardware vendors won't produce Linux drivers nobody can force them.
But the important lesson is to not buy a Windows computer and bitch when it isn't a good Linux computer. They are not equivalent, the same hardware is not supported on both OSes (try putting Windows on a RaspPi) and unless you want to have to deal with faulty firmwares and have to stringently analyze every part you buy to make sure its supported hardware (principally because hardware distributors are garbage at mentioning Linux compatibility anywhere) then you should just buy a Linux computer from thinkpenguin, system76, or any of the other actual Linux hardware vendors that will provide you a system that given whatever version of Ubuntu's kernel it is running, and beyond, you know the hardware will work out of the box on any distro. That is how to use Linux.