You can feel free to uncheck the two opt-in boxes for iTunes special offers and Apple product information, and then you don't need to give Apple your email address either. Just pick a place to save the executable installer, and off you go.
The 78 MB iTunes download should only take a few minutes, depending on your network connection -- but it's important to note that you're not only getting iTunes. There are some ridealong components as well. Apple's QuickTime media architecture is needed to allow iTunes to play and authorize content from the iTunes store, and the Apple Software Updates utility will help keep your copy of iTunes up to date.
Like any typical software installation, you'll need to accept the license terms and click your way through the options for the install.
You'll also have to decide if you want shortcuts for iTunes and QuickTime on your desktop, if you want to make iTunes the default audio player (taking over from Windows Media Player, in a typical Windows setup) and whether you want to automatically update iTunes (the aforementioned Apple Software Updates tool). Pick your choices, and install.
When iTunes launches for the first time, it's more questions for you (when will it end?). iTunes will offer to find your existing media files that it can play natively and add them to your library; it gives you a separate option for importing WMA files, which need to be converted before they're playable. If you don't want all your WMA content in iTunes, uncheck this option.
The next screen is where you decide how much power to give iTunes over the content in the iTunes Media folder (where it puts your content, by default). Allowing it to keep the folder organized means that your file names and folder paths will change automatically if you change the song names, artists or album assignments on individual tracks. Choosing to keep the files organized manually gives you more direct control, but you may see some divergence over time between where you think the music lives and where iTunes thinks it should. (For any track in iTunes, you can always right-click it to show the original file on your drive.)
iTunes is also happy to download some eye candy, if you let it. Once you have an iTunes store account, iTunes will be able to get album artwork for music that needs it, on request.
Pass through the option screens, and you'll see the iTunes tutorial listing -- feel free to explore any and all of the video instructions, or just close that window to go to the main interface.
That's the whole install process -- now plug in that new iThing and have fun!