Linux

Specifically, no. Far less malware on Linux. But it's still a computer system that can execute code.

It's a problem anywhere, centralised software repositories help combat it to a degree.

Yes, much of the web is hosted on Linux servers, and only growing as more and more people start playing around with self hosting projects.

Malware sadly is a problem everywhere, but it is arguably less so on Linux. First, Linux is less popular so less malware is written for it to some degree. That doesn't mean no malware, but if you're trying to pwn people hitting a website you'll get more targetting windows, android, or iOS than Linux so it's a little less prevalent.

Second, it could be argued the security model of Linux is more secure than windows. This is a far more contentious point, but I think that simply from having more eyes on the code Linux has a more secure model. Windows relies on security through obscurity a great deal, and if you talk to cybersecurity experts they will often tell you this is no security at all.

Lastly, because software on Linux is typically installed through centralized repositories of binaries or sandboxed app images, you have to go more out of your way to get dodgy software on Linux. The tradeoff there is that a lot of proprietary apps and helper programs that come with some tech will never be available in the repos and that can send some new users to try finding them elsewhere with all the risks that entails. Some distros go for a middle ground with access to things like the Arch User Repositories, but Ubuntu's solution is using things like PPA's to add extra software repositories.