Adding can improve performance a bit, but only if you have too little RAM. If you already have 4GB of RAM, then there won't be much performance gains. Memory hungry apps will perform better like Photoshop.
SSD only makes the laptop load and save faster. The biggest improvement will probably in booting up Windows. Probably as fast as 25 seconds (maybe less).
Upgrading the CPU can help, but only if the CPU is supported by the BIOS. If the BIOS does not recognize the CPU, it most likely will not even boot. Also, many laptops have the CPU soldered into the socket.