Need advice on Windows installation

Hey, guys, so I need your help.
I have an ASUS laptop with pre-installed Windows 8 Home(UEFI). I've additionaly installed Ubuntu alongside. After a while, I wanted to uninstall the Ubuntu and install another distribution but I wasn't sure how to do that, and the guides online just made it worse, as I formatted the Linux partitions but couldn't uninstall GRUB. So, now my HDD looks like in the attachment.
I have the possibility to upgrade through Dreamspark to Windows 8.1 or to Windows 10, but would like to have a clean install.
So, my questions are:
1. Should I get Windows 10 EDU or Windows 8.1 Pro? I'm not sure W10 is ready, and having the 8.1 will give me the possibility to upgrade later.
2. What do I need to backup and how do I do it? I don't really have an external HDD, so I can't backup all my data on the D:\ partition. How do I backup my current W activation key? Will I need the restore partition? What about the recovery? Ideally, I would like to have a clean install, formatting everything, except D:\.
3. What is the correct way of uninstalling Linux?
What do you think? And sorry about the mess on the HDD.

You can download Windows 8.1 install media here, http://windows.microsoft.com/en-us/w...-refresh-media that will use your embedded 8.0 key. Verified it myself on my ASUS laptop that came with 8.0 Core. That will let you skip the 8.0 to 8.1 upgrade. I just backed up my user folders, Documents, Pictures etc to an external hard drive. Then I wiped all the factory partitions and did a clean install. If you boot from the install media and select custom install, you will have the option to delete any partitions you want, and create new ones. I've done it that way just leaving my Data partition. I then install Windows to the free space at the front of the drive. It then creates all the partitions it needs automatically.
http://www.eightforums.com/tutorials...ad-create.html
http://www.eightforums.com/tutorials...e-windows.html
http://www.eightforums.com/tutorials...ndows-8-a.html
http://www.eightforums.com/tutorials...ndows-8-a.html

I'm currently running Windows 10 Enterprise on that same laptop. No issues with hardware etc. If you do the free upgrade from 8.1 Core your going to get 10 Home, just so you know. Once you do the upgrade and activate Windows 10, a hardware ID is stored on the activation server. You then have a Digital Entitlement for Windows 10 on that PC. When you do a clean install you just click skip when asked for a key. Then once the hardware ID is checked and verified it activates. I'm running Windows 10 Education on my desktop PC. I have an MSDN subscription so why not. It has some features Pro doesn't, namely Windows To Go. It has more features than Pro but not as many as Enterprise. IMHO if you have the option, I'd pick Education over Pro.
https://www.microsoft.com/en-ca/Wind...siness/Compare

You can get English Windows 8.1 install media here, http://windows.microsoft.com/en-us/w...-refresh-media
And English Windows 10 install media here, http://www.microsoft.com/en-us/softw...load/windows10 << No Education version there though, just Home and Pro.

NavyLCDR said:

Changing languages like that from the language that came installed on the computer will require a new product key or Windows won't activate. For example, computer comes with German Windows 8, he downloads English Windows 8, the English Windows 8 won't be able to use the product key stored in bios because the stored key is for German Windows 8. Product Keys are both language and version specific.

I wasn't aware they were language specific? First I've heard of that, other than the Single Language version having its own set of keys?