Music video - walk me through the conversions?

I'd like to edit together a music video for YouTube, using the following three original files:

- an AVI that is 640x480, 30fps, 14.95Mbps (with audio at 11.024kHz, 88kbps - this audio will not be used in the final)

- an MP4 that is 1280x720, 29.642fps, 11.86Mbps (with audio at 48kHz, 63kbps - this audio will not be used in the final)

- a WAV that is 44.1kHz, 1411kbps (this will be the final audio, exclusively)

I'd like the final product to be 1280x720, with black bars on right and left when the video from the AVI is used.

I tried converting the video files to Apple Pro Res 422 in Compressor, but when rendering, sync would go wildly and randomly out.

To what format(s) should I be converting each of these three files in order to have a smooth and successful project with minimal rendering?

Thank you in advance.