As the final result is progressive, then you need to choose a non interlace codec.
DV is standard def and interlaced (lower) so a poor choice for your manipulted pictures. You still haven’t told me what the animation codec is but my approach would be to use an HD sequence like ProRes with Dominance set to none. Exported animation would be preferably in the same codec and the manipulates stills also in ProRes. Also match your pixel aspects carefully. Try to make everything the same.
When exporting through Compressor, the resulting images will be progressive which is best for web. Compressor can then scale down to the required web size if non HD material is required.
My understanding of YouTube is that 1280 x 720p is their preferred pixel size for HD content but check first before making a choice on sequence settings, frame rates and files.