Hey there, Kreljcina
Basically every 2.5" HDD would be compatible with your laptop as long as it's up to 2TB (not sure about bigger HDDs, but anyway you'll be OK with any 2.5" 500GB drive). You could take a look at the WD Blue and the WD Black mobile drives. The WD Blue mobile drive is a simple and reliable HDD for general everyday usage, which comes with a 2-year limited warranty. However, if you want a bit more from your HDD in terms of performance, you could take a look at the WD Black mobile drive. It's fast,reliable and designed to handle better gaming, demanding programs, video editing etc. and it comes with a 5-year limited warranty. You can take a closer look at those drives' features here:
WD Blue - Mobile
WD Black - Mobile
As for the RAM sticks - from what I found on the web, your laptop comes with a 2GB DDR3 (1,333 MHz) stick and supports RAM of up to 8GB. If you want to upgrade and add another 2GB RAM stick, you should get one which is DDR3 and has the same CAS latency, timings, and voltage as the one you already have. However, if those things match you can add a RAM stick which is a different speed in case you don't find a stick which matches yours. If you don't want to risk it, it would be a lot easier to get a new 4GB DDR3 stick (or 2x2GB RAM sticks) and replace the existing 2GB RAM stick.
Here's a helpful article on how to find out everything you need to know about your RAM, without opening the computer: http://www.howtogeek.com/175434/how-can-i-check-my-computers-ram-configuration-without-opening-the-case/
Hope that helps.
Boogieman_WD