What I already have :-

OS = Win 7

CPU = Intel Core i7-3840QM CPU @ 2.80GHz

MOTHERBOARD = Alienware M14xR2 (U3E1)

RAM = 16.0GB Dual-Channel DDR3 @ 798MHz

WIFI = Intel(R) Centrino(R) Wireless-N 2230

GRAPHICS = 2047MB NVIDIA GeForce GT 650M

Can I install Intel® WiFi 6 AX200 M.2 Adapter or  Intel Wireless-AC 9560 M.2 2230 Module w/ Dual Band 802.11ac, Bluetooth v5.0 ?

If not then what's the best M.2 based option so that I can use 5ghz.

Apart from that can I upgrade CPU, Ram, bluetooth, Graphics card etc ?

My 1st choice is to avoid using USB adapters.