lion reinstall

If you bought the Mac with Lion installed and registred/accepetd the iLife apps on App Store you'll be able to download iLife from the App Store after Lion installation

If you mean booting into Recovery HD and selection Reinstall OS X Lion, No, but as with any major change to your system, Backup first

Yes.

Open App Store, select Purchases, you'll see the list of your purchased Apps. If you never bought anything there should be iPhoto, iMovie and Garage Band.

Andy Eastwood wrote:

Lion and iLife were already on the Mac. I didn't do anything with the App store to authorise the ilife products. Is this the same as what you are explaining?

Restoring iLife applications after Internet Restore of OS X Lion

If you reinstall Lion on a new Mac that shipped with OS X Lion installed, on an erased or replaced hard drive, you can download iPhoto, iMovie, and GarageBand from the Mac App Store.

1. After installation, start from Lion.
2. Double-click the App Store icon in the dock.
3. Enter your Apple ID and password.
4. Click Purchases.
5. If you haven't previously accepted your bundled iLife applications within the Mac App Store, you should see your iLife applications appear in the Accept portion of the screen. Click Accept.
6. You may be asked for your Apple ID and password once again. Your iLife applications now move to the Purchased section. These applications are part of the software that came with your Lion based computer. Your account will not be charged for them. Click Install to compete installation of your applications.