Question on Upgrade - M2 SSD and RAM - HP Probook 440 G7

[AndrewOCY]

Hi,
I want to upgrade the M2 ssd Drive and Ram capacity. Currently it comes default 256gb ssd and 8gb Ram.
Noob here in regards to these stuffs.

For Ram 
Can I get a 16gb (single ram stick) first - KVR26S19D8/16 , then at later date, buy another 16GB ram of the  same model code?  Is this possible?  or should I get 2 of these at the same time. Not sure what it means dual channel ram - does it means I need to get those specially made single package - 32gb RAM (16gb X2), instead a single 16gb, then later another 16gb in the future.

For M2. SSD. 
I am thinking to upgrade the NVME ssd to Samsung 970 pro NVME M.2 SSD 1TB.
Is it compatible and performance increased?
Or should I get this instead - Crucial MX500 1TB 3D Nand M.2 Type 2280 SSD (CT1000MX500SSD4)?

Thank you.

[banhien]

@AndrewOCY 

Manual:

      http://h10032.www1.hp.com/ctg/Manual/c06481641.pdf

1. RAM: Yes, you can use single 16GB now then add 16GB later (total 32GB).
2. M.2 SSD: Yes, you can replace existing one with 1TB or 2TB Samsung 970 EVO and  add 2.5" HDD/SSD to your machine but you need   Hard Drive Hardware Kit (includes hard drive cover and connector) part # L44510-001

Regards.

[AndrewOCY]

Thanks for the info on the RAM and drive.

So to confirm, this Notebook supports - PCIe Gen3x4  - as the Samsung NVME requires this Interface Type. Am I right?  The document link - only shows PCIe only. My current 256gb NVME, I will replace it then.

As for the Hard Drive Hardware Kit (includes hard drive cover and connector) part # L44510-001 - I don't think I need it, as there'a an existing drive 1TB Sata HD 7200rpm installed.

Thanks