What "VNCServer" exactly did you install, and how? What is your end goal? Do you want to share the desktop of the physical console, or run an additional independent session via VNC? What VNC client is used on the Mac?
I'm not sure what is included/enabled by default with the Gnome (as opposed to Unity) desktop, however you may already have the Vino "Desktop Sharing" VNC server installed - and possibly already running. That might jive with the fact that you apparently get a refused connection on 5900 even though the VNCServer startup message indicates that it is starting on display :1 (which would normally correspond to port 5901)
Perhaps we should start by looking at exactly what VNC server processes and ports are running / listening:
Code:
ps -ef | grep -Ei '[v](nc|ino)'
sudo netstat -nlpt | grep -Ei '[v](nc|ino)'
on the server