With all the “security updates” that I receive, is it still necessary to install additional protection? If so, what should I use? 
Wrong section, I think this should be in the generic chat or applications?
Apart from the security updates, I would suggest you use common sense, it will project you far better than any security software ever.
One of the reasons why you are receiving security updates is to prevent you needing additional protection - most of them protect against vulnerabilities which no one has exploited but which someone has discovered.
It saves creating a whole industry to close the stable door after the horse has bolted.
I have always suspected that some of the unpleasant thingies affecting us are made up to provide another industry - bring out a new OS, bring out a new virus to generate revenue. Am I being cynical? 
Apart from the security updates, I would suggest you use common sense, it will project you far better than any security software ever.
+1 to this. I once worked on a customer’s XP machine that had the full complement of “Internet Security Suite” software and I still had to format and reinstall the the OS b/c it was so riddled with viruses. His Internet history was filled with blatantly questionable websites (not necessarily porn, but the ad-filled, million-popup type sites). When asked why he was attacked by so many viruses in spite of his protection, my boss simply told him “It was you”.
OTOH, I’ve run XP machines with no AV protection for a limited amount of time (I do not recommend this in any way though) and didn’t encounter any problems, simply because I have the sense to know what is safe and what isn’t.
If you are really paranoid, you could attempt an install of clamav. There isn’t a great need for you to do this, though, unless you doubt your future judgment. Linux malware is out there, but it occurs so infrequently, good sense is the only protection you need. 