This can absolutely be done easily, as long as you have a basic, fundamental understanding of video tracks and compositing and how to use the Ultra Key effect. The quick gist is this: Place your "background video" on Video track 1, place your green screen shot on video track 2 over the clip on V1 and then apply the Ultra Key effect to the green screen clip and key out the green. You can easily delete the audio from the green screen clip by Opt/Alt+clicking the audio clip and deleting it (or using the Drag Video Only icon from the source monitor when you initially add it to the timeline).
Try this article for a bit more detail:
Green Screen: How to chroma key in Adobe Premiere Pro