We have a 8 TB file server in our office which is running Ubuntu 10.10 and it has been performing good. Ubuntu or any distro should not be the cause of issues. The disks are raided with mdadm and no issues there as well. You will need to know some mdadm and you can manage the disks easily. You can samba/ftp/nfs the shares easily by installing the approx servers in the ubuntu machine (should not be hard to set it up).
You can back it up with rsync. Setup auto backup (cron should be your companion) and have it backup the file to your backup server.
If you need the fileserver to be on wi-fi only, any fairly new machine (made in the last 3-4 years) should work good with Ubuntu, as Ubuntu will have drivers for them out of the box. Else you will need some wifi driver tweaking which might be a pain point.
Not sure about the print server part though, I have not run a print server on Ubuntu. But my trust on opensource makes me think it will work wonders. I will have others comment on a good print server if they have run one.
Last edited by abi0909; 03-10-2012 at 02:12 PM.