Doug,
Far as I can tell, if you hilite text on a page, then right click on the hilited text, you get a context menu at the bottom of which is 'Search selected text', click on that and you see the list of search engines selected under 'Tools -> Search engines...'. Otherwise I guess you need to add search engines to your favorites list. EDIT: only the one at the top of the context menu list actually works...
Can't load files here either - probably should file a bug on that one. EDIT: looks like it was reported as #7 under qtwebengine-os2.
Regards,