Unfortunately, CPU and graphics upgrades won't work. Laptop graphics are usually integrated and unfortunately, your CPU (the Intel® Core™ i3-5157U Processor) uses a BGA socket which means the CPU is also integrated into the motherboard.
If you want to upgrade the CPU and the GPU, you need to swap in a new motherboard which is usually both costly and risky.
It will take up to 16GB of DDR3L-1600. Samsung and Hynix are recommended.
The HDD can definitely be swapped out for a SATA SSD. There also seems to be an M.2 option but this can only be confirmed by opening up the laptop.