Here's my question: how comfortable are you with reinstalling windows? Do you have the windows 8 cd? Or was your manufacturer cheap about it and only provided a recovery partition. If you're the latter, you might want to hold off, whereas on the former you should be fine. Likewise, do you have a way of backing up your media? If not, once again you might not be in a position to go messing around with your hard drive. If you do, or if you can just borrow an external hard drive for a day, then you should be fine.
With that out of the way, then yes, that tutorial will pretty much do it- It's what I would do at least.
How large do you want your partition for ubuntu to be? Remember, you can easily access your windows partitions (with all your documents, media, etc on it) easily from ubuntu, but you'll have a little more difficulty accessing your linux partitions on windows (you'll need to install a program to read them).
Generally speaking
256-512mb for /boot
10-20 GB for / (root )
1x-2x your ram for swap
and as much as you need for /home
Swap and / (also known as root) is required- / is the actual system with everything in it, and not having any swap can make your computer unstable. If you don't set a specific partition for boot or home, it will just default and install it into the partition you set for root.
As for learning more about Ubuntu: if you want really. For me I learn best hands on- just jump into it and learn. Ubuntu might not be everyone's favorite, but it's easy to learn and it does a lot for you. If you're a root user with your android, or if you've hung around XDA any bit, then you should have no trouble (used to searching up everything yourself on google, what root does).
Of course you could be in a hick if you mess up, which is why I wanted to make sure you could recover your PC in my first garble of text
