I just upgraded my 2009 macbook to 8 gbs of RAM, its awesome now :)
To find rather its ddr2 or ddr3 and to find the MHz: go to "about this mac" under the apple logo, and it will have info about the memory. My guess would be its ddr3 and ~1066 Mhz but i could be wrong
Another way to find info on the RAM is to look at the box which you got your new RAM from, other than the size all info should match close to the original in order for it to work with a Mac.