I've never OC'ed myself. However I would assume raising FSB will raise temperatures a little more than just changing the multiplier, but that's just my hypothesis. You need a good aftermarket cooler to get a good OC anyways, so to answer your questions I will go ahead and say yes.
The stock FSB is 333MHz, allows for 667MHz RAM. To achieve a FSB high enough for 800MHz RAM you need 400MHz on it. So what you will have to do is go into the BIOS and look for an option to overclock the FSB (increase frequency). If you want to keep the overall clock at 2.4GHz you will have to decrease the multiplier. I'm not sure if reducing the multiplier and increase the FSB will keep the same temperature, so keep an eye on it. But if you want to go ahead and overclock the overall clock, just increase the FSB to 400MHz and lower the multiplier to 6 (2.4GHz total) . Then watch temps under load. If they're nice, increase the multiplier to 6.5 (2.6GHz total). Check temps under load. Lastly, if you want to keep going, do the same for 7 and 7.5, however I doubt you will go any higher.
I've overclocked the cpu to 3.0ghz on air cooling. Temperatures weren't a problem at all. My case remains cool as 24-29C at all times. Soon as I purchase a 3rd party heatsink and fan. I MIGHT try to go to 3.2ghz. Let's say, I overclock the cpu to 3.0ghz. Then what would I have to do with the multipliers?