Performance on Mac OS X is great. I've been able to run Microsoft Office, iWork, and NeoOffice without any problems.
I don't think Mac OS X will run on the Mini 10, but it will run on 10v. However, at this time the internal microphohne, headphone out and microphone in ports don't work and the card reader only works with SD/SDHC cards. This will probably change as the 10v is still relatively new, and you can still use a USB headset as a workaround.
For college work, I think a netbook would work out perfectly for you. From my own experience, I've found it to be much easier to lug around and the battery life is awesome.
With that being said, I'm still not using it as my primary machine. I've got a 15inch Macbook Pro for heavy lifting, i.e. Photoshop, World of Warcraft, etc. But I am finding that it's much easier to pull out my Mini when I just want to browse the web or use it while lying in bed.
My recommendation: get the Mini 10v. It will serve you well and if you find you need more power, you can save up for a Macbook Pro 13inch later on.