Well, AppleCare is technically only a two-year extension of warranty anyway. It brings everything up to 3 years total, not 3 years added onto the factory one year. So yes, basically you will get 2 years off of AppleCare, but that's the same amount you would get if you bought it at the same time you bought the computer as well. 🙂 You do have to buy AppleCare before the factory warranty runs out though, and make sure that you have your AppleCare registered before the warranty runs out. (You can do that by calling or sending in the card that's in the box.)
And...to organize your photos in iPhoto...go to File->New Album to create a new album, and type in the name you want it to have. Then you just drag pictures from your library over to the album you want to put them into.
To e-mail photos at a smaller size (this is in iLife '04 but it should be similar if not the same in newer versions), while in the library or looking at an album, highlight the pictures you want to send...if it's just one, click on it...if it's more than one, click each one while holding down the Apple key. Then release the Apple key and click on E-mail (which is in the Organize section), the size can be selected in the dropdown box...Medium should be good. If they're wanting to print them, they will need Full Size. Titles and comments tend to not carry over well to Windows or other mail programs (in my experience) so if they don't have a Mac I would uncheck those options. Then just hit compose and you're done. 🙂