[https://www.youtube.com/watch?v=nGcaMWJadoc|Here is a video] on how to remove the bottom plate so that you may access the ram and SSD.
You'll notice the ssd is m.2 form factor and not 2.5" sata and is upgradable, the above video shows the process.
The ram can also be upgraded easily while your in there, there are just two little metal clips that must be pulled apart, [http://ww2.justanswer.com/uploads/operab/2011-11-15_025923_remove-replace-laptop-memory.jpg|this image demonstrates.]
When it comes to what SSD to buy and where to buy it, it's completely down to how much money you want to spend, if you want a very good m.2 SSD, the Samsung pro is a good pick (I use a Samsung SSD 850 PRO 256GB myself).
Buying advice: pick the SSD you want (agree with it's general price) and shop around for a bargain.
Ram, again, is down to how much do you want spend. If you want 32gbs you will need to buy '''2x16gb''' sticks. The type of ram is "DDR4 PC4-19200 2400MHz 260-pin SODIMM" sounds like a mouth full but if you put "32 gb buy" at the end and google it, you'll get quite a few results to consider.
Hope this helps, let me know if you need anything else.