Ask for clarification. Generally, a full res version can be uploaded to YouTube to get max quality. YouTube even accepts ProRes files. I don’t know why a separate version would be necessary.
Synthetic music (like electronic, dance, synthesizers, etc) can often benefit from using AC-3 with at least 384k bitrate instead of AAC. AAC can introduce excess distortion on synthetic sources that sometimes doesn’t sound good.
Good call.
Unless you absolutely need constant bitrate mode (which is not needed for YouTube or local media player playback), then quality and file size can often both be improved by using VBR mode at 68% quality (CRF 16). 100Mbps is targeting that quality range anyway, but variable bitrate mode can breathe if it needs more bitrate for tough sections, and can avoid wasting bits on the easy sections.
If the recording is YUV 4:2:0, then there is no point in making a ProRes file (which is 4:2:2). The libx264 file would be as good as it gets without going lossless.
If your recording actually was 4:2:2, then skip the libx264 stuff and go straight to ProRes or DNxHR HQ for archiving, YouTube, and future transcoding.
If unsure what the clips are, click on a clip then go to the Properties panel. If the format is yuv420p, then it’s 4:2:0. If the format is yuv422p, then it’s 4:2:2.