Will Compression/Format of Audio Change when Uploaded to YouTube? If I have a .wav audio file, put it in a video file, say a .wmv, as, if I'm not mistaken, that format basically just uses .wav for its audio, and upload said .wmv file to YouTube, will the compression or format of that audio change?

In other words if I have a certain sequence of bytes present in the original audio file and I upload a video containing it to YouTube, if somebody downloads a copy of the isolated audio from that video, will that sequence of bytes be present? I couldn't find a definitive answer anywhere, and hoping someone on SE can help.

Again, I'm asking about only the audio, not the video.
Youtube generally reencodes all videos you upload to youtube to ensure compatibility across various platforms and to provide smaller versions of the videos for users with slow internet connections. So yes, both the video and the audio stream of your video file will be compressed and reencoded when you upload it. If someone uses a third party tool to download the video from Youtube, they will only be able to grab that reencoded file, never the original upload. Because Youtube compresses the video very heavily to reduce file size, there will be a noticable quality drop in both video and audio, which is a complaint many video editors have about youtube (though there isn't really a well-known alternative that doesn't reencode videos on upload). Youtubes will reencode the audio to m4a and aac files in various bitrates, as well as some low-quality ogg files.

If you want people to be able to download the unaltered original, you should provide a download-link via a file hosting service such as Dropbox or Google Drive. I believe if you have a Vimeo Pro Membership, you also have the option to allow people to download the original video, but I'm not sure about that.