virtualbox.org

I am running VirtualBox on Ubuntu 14.04 LTS host with various Windows VMs, no problem. I'm familiar with the Guest Additions to get Windows display drivers, so VMs can go full screen.
An associate has just started with VB (current release,) he's running Windows 7 host and has a Ubuntu 14.04 LTS Desktop VM. Asking the Ubuntu VM to go "full screen" results in a 4:3 window on his 16:9 format Windows screen.
Question 1: Am I right that with regards to screen drivers Guest Additions is only pertinent to Windows VMs?
Question 2: It appears that he can not adjust screen resolution of the VM in VirtualBox Manager Settings to make more use of the host's screen. Is there a tweak somewhere that we haven't found?

http://www.virtualbox.org/manual/ch04.html

All guests need the guest additions to have access to higher screen functions.

Thank you. Clearly the assumption that Guest Additions was specifically for Windows VMs was wrong. Nice to see the other capabilities such as host folder sharing will be available as well.