You can use crucial.com and look your model number to find the speed and maximum amount of RAM that you can purchase for your laptop. You can use the service manual for your model to find that information as well, plus the steps for replacing the RAM modules.
The number one factor in overclocking is heat, and given that laptops and heat have a complicated relationship, I wouldn't recommended it to anyone simply because the small gain you would get before burning the thing up wouldn't be worth it.
Your processor is unlikely to be able to be overclocked anyway. Replacing it is also just as unlikely.
My Personal Method for Speed:
One of the ways that I keep my computers fast is back up my documents to the cloud, portable-ize my software, and reinstall Windows when I start having significant enough speed problems.
The best way to make an old computer blazing fast:
Replace it, or only run MS-DOS.