I'm assuming a lot here, but it's all assumptions based on what I've seen and read. When you upload images to the .mac gallery 5 differrent versions are made for each photo so they will display nicely in any browser up to a certain resolution. You can poke around in your iDisk to see them.

After that another copy is made of your file that supports prints up to 16x20 prints depending on the original file size. In my tests, my 3072 x 2304 photos were converted to 2880 x 2160 when downloaded. I'm not sure if that is the top resolution .mac supports but it's worth experimenting with.

"With iPhoto '08, .Mac members can easily create a .Mac Web Gallery with just a few clicks and choose whether they want to make their albums available to everyone or limit access to specific people, allow visitors to download high-quality images suitable for making up to 16x20-inch prints..." - Apple PR

If you need files bigger than that I would suggest using the File Sharing templates on .mac or getting your own web space and building a portfolio. Maybe there will be an option for professional photographers with the next update of Aperture?

The other day I was mucking around on my mac and the little icons in the tool bar jumbled around. In confusion I did a bit of playing around with the keys and realized if you hold down the apple key and click on the icons, they become movable.

So you found out the little secret, huh? Actually most native apps for OS X have this handy feature. Try control-clicking a tool bar at the top of a window and you might find tons of buttons you might not have known existed. Or just look for "Customize Toolbar" from the menus.

Mail for instance has tons of buttons hidden that not many people would find useful in an effort to keep the app nice and clean.

A lot of options are hidden under the surface. Try control-clicking the dock or any of the apps on the dock and you'll see more options than you may have bargained for. If you are new to the Mac, hopefully you will learn to "just try it." The Mac rewards you for clicking around to discover the details.

All the options for burning and ripping are under the preferences menu in iTunes. Click the Advanced tab once you're in iTunes preferences and click on either the 'importing' or 'burning' sub-tab.

Under importing you will see a variety of formats that can be used.

AAC is supposed to be the successor to Mp3. It is the format used by the itunes store and it's supported almost universally. Extensions include m4p, mp4, AAC, and m4a. it supports different bit rates and is the default setting for importing cds to iTunes.

AIFF is lossless and uncompressed. It was first invented by Apple in the late 80's. It's the leading form of audio file used by audio and video professionals. This format is the highest quality, but also one of the biggest files.

Apple Lossless Encoder is encoded in a m4a file. It's good for making compressed versions of lossless files. Compressed files take up about 50% less space than the originals.
Mp3 is perhaps the most familiar, so I won't go into detail here.

Wav is only around for compatibility with PCs. It might be good for some things, but I don't suggest using it unless you have to.

I would use AAC if you're only using your music for iTunes. You can always convert songs to Mp3s in iTunes by right or control clicking a track and selecting convert to Mp3, which is a good alternative to AAC. If you plan to use your files in more places than just Apple products, go for Mp3.

As far as burning CDs...
There are three formats: Audio, Mp3 and Data.
Audio is your basic music CD that will play in your car or home stero. Mp3 is for CD players that can read Mp3 CDs. You'll have to look in the fine print to find out if your player can do it. One advantage is the tracks take up less space in this format, so you can get a ton on a CD. Data CD is usually used for transferring music from one place to another. The files are unreadable by most CD players, but are perfectly readable by other computers. The files take up even less space, so you can actually fit a good amount on a regular CD.