Music
I think you'll find this subject covered at length in another string.
Basically, you'll need copyright clearance from the music publisher to use the song and usage clearance from the record label, if you are using the record. This not an either or situation, but a both. Almost without doubt, they will require payment for this.
The only exception I know of, is if you are a film student based in the UK and your indivdual college has a copyright clearance waiver. In which case you may be able to use the music on student films without obtaining permission, provided it is never sold or used for profit. The college should have a copy of the document and should know themselves what they can and can't do.
Any attempt to use someone's material without legal permission is theft and treated in the courts accordingly.
A better route is to find local bands who have recorded a demo disc and get permission from them to use their songs. You can get the demos sent to you by putting an add in the local music shops that say "Songs needed for local film project, please send CD to PO Box etc" You will definately get a response.