Yeah what you mentioned in the OP is a little generic.
I don't think you should buy a new iMac just because it' beautiful, there has to be some logical financial decisions unless you just have tons of money, then you should wait and buy a Mac Pro.
Why not buy a nicely upgraded iMac, and sell your Windows desktop? Maybe buy an iPad or something too to have fun with, with the funds from selling your desktop? You can run Windows programs on your iMac, and it'll most likely handle everything you throw at it, though maybe it won't play games at 600fps, idk if that's an issue.
If you aren't willing to part with your desktop PC, I'd say get the laptop. It just doesn't make a lot of sense to have two desktops.
if you do opt for a laptop, the rMPB is a fine choice. I don't see the ethernet being an issue, university wireless is usually top notch, and you could buy an adapter for like $19.
Since it appears you want to do graphics editing, and if you select a laptop, I would make sure to max out the ram as much as possilbe, and be sure that you're getting a 256 SSD with the rMBP.
I'm not sure what is standard, nor what your budget is.