Does apple have terms and conditions regarding ownership of content?
I don't think there is an actual Terms and Conditions page. The nearest would be this page:
It does mention copyright violation as a reason for removal. There are any number of podcasts with 'mixes' using commercially available recordings without clearance: this is obviously a violation of copyright and as I said if spotted will get the podcast removed. Also anyone doing this lays themselvs open to legal action from the copyright owners (there was a post some time back from a podcast creator who was being sued for $25,000 for using material without permission, though I never heard the outcome).