1) What is root, and why would I want it?
Root is basically the linux equivalent of the Administrator account in Windows. By default, your phone does not give you access to the root account. This limits you on what you can do to your phone to basically what Verizon allows you to do. By rooting your phone, you are given full access to the file system, to make whatever changes you want, and do whatever you want with the hardware. The primary thing people with root will do is installing custom ROM's. Typically a custom ROM will have more features and less bloat, and run faster than an official Verizon release. This varies from ROM to ROM though. You can customize the entire GUI, you can do things such as wireless tethering, run apps that weren't meant for our phone (such as Nexus One stuff), and plenty of other things.