Why should I buy another, more capient hard disk, when I can convert the games I own to take less space ? Really, I don't want to spend money in a useless way, especially if there is another free way to save space.
I successfully installed Debian linux and Ubuntu in another computer with similar specs (but with intel video card ) and it runs smoothly.
Usually I use the netinstaller of debian that leaves out the trash ubuntu install by default ( Unity for example ). If you experienced lag usually it means...
Try to run an ubuntu live and start media creation tool will on Wine. I'm not sure it will work but you can always give a chance. If that does not work you have no choice but access to another windows PC.
Debian 8 netinstall + MATE. Actually I installed on a Intel celeron 2.6 GHz + nvidia MMX 400 (so really old PC ) and it is really fast. If you have a PC faster than that give it a try.
I've read somewhere that RC will not be announced publicy and that daily builds post 14th April are considered to be the RC. I'm not sure about these informations so take with a grain of salt.
Are you able to run an Ubuntu live from USB on your chromebook ? If yes try using WinUSB , it should be compatible with windows 10 too.
Use this guide to install it on ubuntu:
http://dothisbest.com/how-to/install-and-use-winusb-in-ubuntu/
I would recommend a network install of debian 8 with MATE desktop, also recommend to install laptop-mode-tools , cpufreq-utils , cpufreq-indicator to increase battery life.