Memory compatibility and upgrade for HP 250 G2 laptop/notebook

Voxxel

TS Rookie
The laptop is the Intel Core i3 version so it has 2 memory slots,
the existing single RAM module is a SAMSUNG DDR3(L) 4GB 1Rx8 PC3L-12800S 1600MHz 1.35V, part number: M471B5173DB0-YK0.

Normally, I would not buy 2 new modules, only one to upgrade the existing one but if you say the existing one is too slow and worth to upgrade to a faster one I'll consider to get a full pair or RAM. I know it would be even faster with 2x8GB but I'll stick on the 2x4GB because of money issues.

I see there's a lot of similar part numbers, started with M471B5173 and ending with various other letter combinations, such as EB0-YK0, BH0-CK0, QHY-YK0, QH0-YK0, etc,

and also there's an B5273 series
M471B5273DH0-CH9,
M471B5273DH0-CK0,
... and of course there are also heaps of other brands.

I would like to know the compatibility to make myself sure I don't buy something which is incompatible with my laptop or with my existing RAM module (taken I keep it).

So would you please lighten me up

1. Should I replace the existing RAM module in order to earn considerable speed-up?
2. If 1 is True, what pair of RAM would be sufficient?
3. If 1 is False, what kind of RAM modules can I use on the other (free) memory bank to make it compatible to the existing module (is dual-channel a thing in laptops too?)
  • - Are the other M471B5173xxx-xxx modules compatible too?
  • - Are other RAM brands/series compatible too?

Thank you in advance for your help! <3