Q: I want to do a clean install of Mountain Lion. Can I do this without a DVD version of the OS, and can I restore only specific things like iPhoto and iTunes libraries from Time Machine backup.

Mountain Lion is only available as a download, so there is no DVD to purchase. What you can do is download ML and then stop it from installing as soon as it's on your drive. From there you can make your own bootable ML flash drive.

When your purchase and download Mountain Lion, it will end up in the Applications folder and automatically want to install. Press Command+Q to stop the install and exit. The installer will remain on the hard drive.

1) Right click on the installer and choose "Show Package Contents".

2) A folder will open on the desktop. Drill down to Contents > SharedSupport and double click the disk image InstallESD.dmg to mount it on the desktop.

3) From here you can either burn a DVD, or copy the contents to a flash drive. Personally, I would strongly suggest using an 8 GB flash drive formatted as Mac OS Extended. You will be able to boot to it in about 30 seconds instead of at least 10 minutes off of a DVD, and it will install MUCH faster. Make sure the flash drive is empty, or you've copied anything off it it you need as it will need to be erased.

4) Don't just drag and drop the contents you see in the open disk image to the flash drive. It won't boot that way as it will be missing some hidden files. Open Disk Utility. You will something similar to this:

5) To accomplish the above, highlight either the flash drive's single partition (as I did), or the item at the bottom (Mac OS X Install ESD), which is what you will see with the Lion disk image mounted. It doesn't matter which one you pick. You'll then have the option to select the Restore tab towards the upper right. Drag and drop from the left column into the Source and Destination fields as shown above. If you've already erased the flash drive, you can uncheck the box. Click the Restore button.

You've just made your own bootable Mountain Lion USB Flash drive installer. Once you boot to the flash drive, run Disk Utility first to erase the drive you want Mountain Lion on, then continue with the install.

As far as restoring your iPhone and iTunes libraries, I couldn't tell you. So I wouldn't do any of the above until someone else chimes in with a way to do that after a clean install of ML.