I'm a network engineer, usually working with Cisco. But recently I had to work with some products that run on Linux, so I had to learn...
Here is a tutoril site for Ubuntu: http://linux-bible.com
If you really want to learn Linux, you need to learn how to use the shell. You will find all the stuff you learn now handy in the future.
I would also recommend Ubuntu.
You can use LibreOffice instead of Microsoft Office and Gimpshop as an alternative to Photoshop.
The message means that GRUB can't read that file. Check your disk.
I would recommend SLES.
I would recommend Ubuntu for beginners, because it is easy to use and there is a lot of material online about that specific distribution.
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