Incessant McAfee Notifications

You're encountering notification spam.

Open Safari's preferences/settings. Click on the Websites tab, then scroll down on the left to Notifications. Remove the offending entry in the right hand pane. You might find something similar in the Pop-up Windows heading below that.

No. The spammers are using that icon to make it appear it's something that belongs to the system. It's not. All you're turning off are notifications other web sites are pushing to your Mac.

I've also noticed a huge increase in McAfee spam emails over the past couple of days. They must have purchased/shared a bunch of email addresses. It will slow down after a while.