Definitely think using a cloud based storage option given your lack of internal storage is the best way to go. OneDrive is useful because it has two modes: online / download on request or offline availability, meaning you can save the storage. In schools, if they are on the education plans you get 1 TB of storage space which is quite a significant amount for cloud-based storage. For GApps, there's Google Drive File Stream (GDFS) which is NOT the downloadable Google Drive app. It's designed for education deployment BUT can be used on a personal device. The upside of GDFS over the standard Google Drive option is that it like OneDrive has a download only on request feature, saving storage and only downloading to your device when needed.
If you are in a government school (I don't know so going to assume?), Office 365 is available by default using eduPASS (email @schools.vic.edu.au), if you don't know what i'm talking about go and see your IT technician when you return to school. Google Apps is also available by visiting
https://drive.google.com/a/edustar.vic.edu.au/ and logging in again with eduPASS details (just make sure your school hasn't already signed up using their own web address first!). If you aren't in the government system, then you'll have to speak to your IT techs to get advice on what your school uses etc.
OneDrive is extremely reliable and is a Microsoft product so you know the reputation is there and your files won't just disappear. The risk of saving to a uni / school account is loss of data once your access is revoked so it's important to remember to get those files and remove them before you lose your access.
Google Chrome is a massive resource hog but not significantly more than any other standard browser. I use Firefox personally for my day-to-day stuff because the aesthetic is much better and suits my eyes more (I don't know what it is, something to do with fonts). I suppose it's something that is personal to you. Choosing a different browser than Chrome purely because of the "resource" reason is a pretty weak reason to justify a browser change... but each to their own I suppose.
For your laptop, make sure you
turn it off rather than
sleep. I am a serial offender with my work laptop, accidentally forgetting to turn it off and just shutting the screen. Doing this it still utilises a low level of power so the best way to give your parts a rest is to shut it down completely. Play around with the power settings and change the screen / sleep settings along with brightness as these impact the battery's overall performance. Another thing i'd keep in mind is that if your laptop gets quite hot due to use, this can slowly damage your parts (ideally the built in fans are enough but not always) so definitely check that Task Manager to see if there's anything that's hogging your resources.
P.s Edge is (generally) a dud, don't use it unless you're using it to download another browser. While it's mostly compatible with everything, it lacks that polish that the more popular browsers have.