Is it safe to have a virus in a virtual machine?

Answer 1

No.

Any data stored on the virtual hard drives of the virtual machines is stored on the hard drive of the host system. When any VMs are in "suspended" state, their RAM content is also saved on the hosts hard drive. Any malware which can access these files can read and modify their content.

Another attack vector would be to target the hypervisor process directly and inject code into it. When one controls the hypervisor, one controls the virtual machines it executes.

A malware called Crisis has been spotted in the wild which targets virtual machine images on the machine it runs on. An attack from the host system circumvents most security features a guest system could have, which means that it would be almost impossible to harden a guest system against this kind of attack.