anti-virus software, clean-up software

Never install any app that claims to "tune up", "speed up" or "clean up" your Mac. These apps exist for one reason: to separate the unwary and inexperienced user from their hard-earned money. At best they do very little, at worst, they can damage your OS installation and cause far more problems than they "solve".

you may want to read Effective defenses against malware and other threats - Apple Community. it's a long article, but worth your time to read every word.

No. Avoid such products at all costs. They will do nothing but cause you grief.

+1 for avoiding grief with unnecessary products.

you're welcome. :)