1. BIOS is best.
2. You overclock all 4 cores.
3. Up to you. The upper limit with stability is about 3.4 - 3.6 GHz.
4. Keep the temps under 70 C.
5. Use software such as RealTemp, CoreTemp, or HWmonitor.
Go through the guides. Then take your core voltage off Auto and set your memory voltage to factory recommended values. Change the System Memory Multiplier from AUTO to 2.00. Then when you increase the FSB, the memory clock will rise in in proportion with it. At an FSB of 266 MHz, your memory clock should be at 533 MHz.
The stock cooler is good up to 3.0 Ghz. Anything higher will require better cooling.
You can easily change it from stock 2.4 ghz to 3.0 ghz simply by changing the FSB from 266 to 333 without any voltage bumps. If you want to go higher, you can do a couple of different things depending on the motherboard and BIOS. You can drop the multiplier from 9x to 8x and usually get higher clocks with lower voltages, but will limit your overall ceiling based simply on the multi. If you leave it at 9x, you will see higher frequencies, but will encounter the need to bump voltages past 3.2 ghz or so.
For instance, my chip requires 1.47500 volts to reach 3.6 ghz and remain stable for 10-20 runs of Intel Burn Test. Nothing less is stable. Also note, that you'll want to determine what you need exactly for your chip, not all are the same. If you find stability at the speed you want, try dropping voltage until it's unstable, then reverting to the last stable setting. Likewise, you can also increment up on voltage until you no longer get failures on stability tests.