[ubuntu] ubuntu 14.04 LTS install on HP Z840, broken characters and how to set network?

Hi,
I have received this new HP Z-840 machine yesterday, the supplier had installed Ubuntu 14.04 LTS server with language set to Korean
After installing CUDA and other packages I saw the sample deep leaing program runs all right, then we decided to change it to Ubuntu English desktop version.
I just tried myself this moing, so I made Ubuntu 14.04 bootable USB stick and changed the boot order to use USB first.
Three problems :
1. during the installation, some characters are not shown correctly(some in white color, here and there making it a little hard to read)
2. I proceeded anyway, and booted again with HDD expecting to see Ubuntu window. But I only see blank Ubuntu window screen. no menu..ctrl-alt-del doesn't work so I had to hard-reboot it.
3. I saw during the installation, there was an option about 'this computer coected to inteet' the check of which was unchecked.
but how could I set network during OS install before it is installed? (in BIOS menu?) or should I just 'try ubuntu' and set IP address there and start Ubuntu installation menu from the GUI? (
(I once saw this menu, but not at the second install, I may be able to start anew but will watch the supplier install it this afteoon. They are scheduled to come today.)
Can anybody give me some answer to any of my question?
Thanks!
Chan