CanWeAddNupediaArticlesToTheWiki

Yes.

How? For example, I'd like to add a new entry to the list on the MuSic page (this was formerly an unbuilt page), for MusicNotation. However, the MuSic page doesn't have a "Edit text of this page" link at the bottom (when this question was written, the MuSic page was unbuilt).

Sounds like you want to know how to MakeaNewPage!

Once you add any text to the MuSic page, you can then edit it using the "Edit text of this page" link. In fact, I did this for you. No thanks necessary. Now go to the MuSic page and you can add text.

More to the point, whenever you see what looks like a topic, followed by a question mark, just click on the question mark. You did this when you first clicked on the question mark after MuSic. After you clicked on that question mark, you saw a big text box with the words, "Describe the new page here." You probably didn't realize that you could just erase those words and type in whatever you wanted!