It is not usual to be able to change the Graphics in a laptop as they are integrated onto the motherboard and not replaceable. I would check this out very carefully with the laptop manufacturer.
Why do you want to install 16GB of RAM. The additional gains over 8GB are minimal and only if using memory intensive programs ie video editing. Are you using 32 or 64 bit Windows. It must be 64 bit to use anything more than around 3.4GB of memory.