Malwaretips are usually pretty reliable so no worries there. It looks like you must have accidentally installed it, probably by clicking a bad link or downloading/file sharing from unsafe sources. It could have been simply an email that looked genuine enough.
Safe Search is no relation to that and is simply an added layer of protection, however it makes Yahoo Search your default search engine, so you may not want to use it.
WebAdvisor usually will warn when something looks doubtful, in supported browsers of course, and your antivirus software provides extra protection.