I use Ubuntu because I'm still new to Linux
Not hard at all, actually. I'd recommend installing Arch first, then Ubuntu.
I remember a "Install ubuntu alongside <current os here>" option. Does that automatically set up grub bootloader to let me choose between arch and ubuntu?
It's i3. I like tiling WMs because it makes your workspace so functional, but they take getting used to when you're used to floating window managers.Your program would open, it just would have no window decoration and you wouldn't be able to move it. See this post.
(EE)Fatal server error:(EE) no screens found(EE)(EE)
You need to install video drivers.Are you using Arch Linux? If you've got an nvidia card, just type pacman -S nvidia and it should work. If you've got an ATI card, type pacman -S catalyst. Otherwise, pacman -S xf86-video-vesa.
Try using just nvidia. 304xx supports my card as well but it doesn't work for me, either. Same error.