1. AppleScript is a powerful, plain English scripting language that allows you to script behavior of many applications. Compared to most programming languages, it's very easy to learn, but it still takes some effort. If you learn it, you might find it very useful. I've learned just enough to write a couple little scripts that I use constantly. Automator is a more user-friendly way of doing some of the same kind of stuff you could do with AppleScript, but it's not nearly as powerful or flexible.
2. Hold down control while clicking to simulate a right click. You don't need to right click on a Mac very often, but it's sometimes convenient. Of course, you can also hook up a regular 2 or more button mouse, and it will work.
3. This always worries new switchers. Most programs can be uninstalled simply by dragging them to the trash. There is often a preferences file that you can also delete, but you don't really need to, it won't harm anything to leave it put. Applications that can't be dragged to the trash usually include an uninstaller.
Congrats on your new Mac, I'm sure you'll love it. I switched a year ago, and now am 100% Mac for work and personal use. I play around with Linux, but really don't have any need for Windows whatsoever anymore (which is really nice).