So, right now, I am planning to upgrade my disk of my current laptop. Later on, i want to be able to use this upgraded hard drive with Alienware 15 R3.

I went through previous forum questions related to M.2 SSD but they are a bit old like Samsung PM951 is not available and have a new upgraded (PM961) version. But I am not sure if PM961 is compatible.

I want to have a 1TB hard drive now. I saw that samsung 960 evo 1tb is not compatible with R3.
What all M.2 1TB SSDs are compatible with R3 ?
Which options do I have if I want to go either size 2280 or size 2242 ?

There are also 3 types of bus for M.2 SSD (SATA-bus, PCIe NVMe and PCIe AHCI).
Out of these three, which all are compatible with Alienware 15 R3 ?