I'm using Wayan's "The Reveal Component" as an information pop-up - info that could change frequently such as news, sales, announcements... Can this modal be used to display a page from my own site? This would allow me to make changes and upload only that page - rather than uploading the entire site (could be 50+ pages) every time.

Is there another approach that would be better?

I answered my own question this time. I added an "HTML Element" into the modal container with:
<iframe src="mylink.html" frameborder="0"></iframe>

The "mylink.html" is the page I can edit. Easy way to update the modal site-wide with only 1 page to upload.

As far as I understand, the reveal modal needs a page to 'sit' on, with the link/butten you click on to make it open.
If you don't want having to upload all your 50+ pages every time you have an update, then make it into two projects; one for the 49+ other pages which are going to be more or less static, and another project for that one page with the link to the modal. And then you link the two projects together in a navigation menu.

It would also be doable with an iframe in that modal, I guess.