These sites have images which can be used for student projects, as long as you provide 'attribution' (cite your sources) in your project's bibliography. You can also search Google Images but be sure to click on the gear icon, select 'advanced search' and under 'usage rights,' choose 'free to use or share.' See more information from Google about this here.
Tools like iMovie and Windows Moviemaker have built in music options for your projects. Here are a few other sites where you can find 'copyright friendly' music to use in your projects. As far as using music from popular songs, the rule of thumb is that you can use 10-12 seconds of an average 3 minute song, more than that, and you are disrespecting the rights of the musicians.