several of my app icons are blacked out. How can I clear them?

IIt sounds like your apps got stuck while updating. First, try a hard reset ( holding sleep/wake button & home button until the screen goes black & the apple logo appears. ) Once the iPad has rebooted, see if the updates are showing in the App Store & try to redownload. If that doesn't work, download the apps into iTunes on your computer & sync the iPad so that the apps will update that way.

Restore from backup.