This is most definitely NOT a netbook, in either sense. It has an Windows 8.1 operating system that works just fine when not connected to the internet (i.e., not a Chromebook). And unlike the netbooks that were widely available a couple of years ago, it has a substantial amount of computing power and graphics capability (my netbook wasn't able to deal with high def streaming video, this one can).
Yes, you can upgrade the RAM, but only to 8 G. Also, it only has room for one chip and make sure you get the right one. As far as changing out the HD drive, I believe you can, but I am not sure which one you could use. Maybe when you change the RAM you can check what is possible with the drive since you have to pull the whole bottom off to access the memory. I've been using the laptop as is and it works well for all I do. I woul recommend using the laptop for awhile before you change anything. Maybe it will work just fine "as is" for you?
It works very well with MS products. If one tries to run very large Excel spreadsheets using Open Office 4.1.1 it will not load them, but this might be the case with any computer - no experience beyond the E3-111-C5GL trying to do this. Internet access is fine.