good morning to all,
Good morning. I'm going to answer a question you posed indirectly. If endless pop-ups and the like are driving you crazy you should download and ad blocker. I think Adblock Plus has an Opera extension, but if not, someone will. I don't have Opera installed on this machine.
please, i wish to know if any of the follows can be downloaded as extensions (plugins)
Probably, but Opera supports its own version of private browsing, and that's precisely what private browsing is. There's no need for any extension/add-on/plug-in
This is not normally handled as a browser element, per se, though many antivirus products place themselves such that they scan URLs before they let you get there.
Many, but for one that works with all browsers, but not as a plug-in, I've always liked Brightfort's Spywareblaster.
pdf document viewer
Too many to mention. Take your pick from Opera's add-on search results.
Look into the EFF's HTTPS Everywhere. I think they have an Opera version, but I might be mistaken.
Don't know about this under Opera.
Brian AKA Bri the Tech Guy (website in my user profile) - Windows 10 Home, 64-Bit, Version 1803, Build 17134
Memory is a crazy woman that hoards rags and throws away food.
~ Austin O'Malley