I am not having any luck with searching for files. I have GB's of Graphics files that I need to consolidate in one or two folders for quick viewing. When I search for "nun" I get results that have no nun in the name. How would I delimit the search so only "NuN' appears in results?
Try filename:nun instead.
SHAZZAM...!
Note that you can also use Tools > Find Files for a more intuitive way to find things, using Opus's own functionality. That lets you specify separate search patterns for names, contents, and so on. Takes up more space, as a downside, but only when you're using it.
On the other hand, the search field on the toolbar is similar to the one in File Explorer and, rather than being handled by Opus itself, the query you type is passed through to Windows Search, which has its own syntax, such as the filename: prefix to restrict searches to names.
Like the rest of Windows these days, the documentation for Windows Search is incomplete, hard to find, and hard to link to because it keeps moving around. 
Some documentation is here currently, but I'm sure Microsoft will break the URL again soon, as seems to be their nature: Advanced Query Syntax.
For people using Windows in other languages, note that the Windows Search / Advanced Query Syntax terms differ per language, so filename: may be something else in other locales.