I am in the same boat so was doing research myself when I stumbled across your page! So far, I have discovered that Rhino is actually a Windows based software, so MACs aren't necessary. Rhino Gold is a new tailored software coming out (if not already) that is tailored for jewellers, but I really don't have any idea if there is much difference. Either way, I have read the more RAM you have on a laptop the better. So at the moment, I'm looking at upgrading my laptop (Fujitsu) as it is almost 5 years old and I doubt it will handle Rhino!
By the way, when do you start your course and where?
1) yes and yes
2) No, since Windows can't handle the high desktop resolution needed for the retina display
3) The people that have them seem to like them but have taken two steps towards to "poor farm"
4) Hard to say. I you use a lot of textures then more video memory will allow more.
6) Yes. If Rhino was my main application and I didn't need a Mac for other OSX based tools, I would not spend the money on a Mac.
You might want to look at one of the custom builders like Maingear, Digital Storm or others. These are PCs made for gamers so they tend to be top of the line in terms of graphics handling.
I use a MacBook Pro for Rhino5 and love it. But you should plan on using Bootcamp and reboot to Windows when you want to use Rhino rather than trying to use Parallels.
You should look into workstations or generally high end gaming computers. You will be able to use rhino with most modern laptops on the market but that does not mean that the program will run smoothly; It depends entirely on what you are going to be using the program for.
You need a good video card (I'd say at least 1G) for rotating around, panning in/out, general work in the model space. And you need RAM for large operation commands / rendering. I had a dell 6400 when I first started (4 years ago). Nowadays, I'd recommend something more like Oasis. Look into Asus for more pragmatic options.
A thin/ sleek 13/15 inch laptop can run rhino but if you are going to be working with complex geometries then it is not a practical investment. At this point I'd say there is no practical laptop solution and it makes much more sense to build a custom desktop.