Have pages not within the TOC or linked to, but still come up
under the Search results. If I do not want these pages to be
searchable, do I apply the Under Construction Build tag, or could I
make it Status > Ready for Review ?
You are misunderstanding what topics go into an output. All
topics go in except those that have a conditional tag that gets
them excluded via the build expression. The fact they they are not
in the TOC and have no links to them is irrelevant.
If you apply a build tag to exclude them, they will not be in
the output but it seems your goal is to have them in the output but
not searchable. Snippet 94 on my site will help you with that.
The Ready for Review status does not exclude topics.
I suggest you experiment in a dummy project before setting
things up in your real project.