1. A lot is different. A lot is the same. The Linux community took a lot of stuff from the Windows OS (and from the Mac OS) during the mid '90's, back when Linux was not eye candy. How long did it take you to learn how to use Windows "productively"? It might take twice as long with Linux. When you do, though, it's well worth the wait. You're rewarded with a clean system, free of hassle (unless you start compiling everything beta) and stress.
2. Looks, but not runs (at least I hope not). Lindows, but yeah, stay away from that distro. Mandrake, SUSE, or Lycoris are right up you're alley.
3. Nah, just don't be afraid to crash your system when you're learning, though. That's how you learn to use Linux. At least that's how I'm learning.
It always a good idea to keep a Windows partition running alongside a Linux partition, just in case you ever need to use Windows for something. It's a lot harder to install Windows once you have Linux running.