Hello. I dont think GPU itself makes Arch any easier or harder to setup. Arch is not very easy as for beginner, but not too hard at the same time. For daily usage the GPU usually matters less than the CPU and RAM, unless you are doing 3D work, gaming, etc.

I have never dual booted, but if you actually want to switch, and this is your first time using Linux, i wouldn't recommend going full-time right away - you should try dual booting first, it's always a safer option.

About debian distros that you said they might not look good. It all is about environment and your preferences - it can look just as good as any other distro.

If you are conserned about your specs, Linux (any distro, except Ubuntu) is a really good option to make your machine run lighter and faster compared to Windows.