Moving a CPU to another computer

I would like to take my current cpu, heatsink, and fan, and move it to another motherboard.
Note: The CPU is a P4 Willamette (socket 478 I think).

Since, I have never dones this before, I have quite a few questions.

1) Do I need to purchase some thermal greese or thermal paste to reapply to the cpu when I move it to the other motherboard? I was told I needed to.
2) Do I need to scrape off the old thermal paste or pad that was between the CPU and heatsink? If so, how do I do this and what precautions should I take? (Be very detailed if you can.) Is there anything I need to be careful not to do?
3) How do I apply the thermal paste, and how much do I apply?
Is this something the instructions will tell me?
How do I know the right amount? What if I miss a spot on the chip? What if it gets onto the area around the chip? Do I need to remove it? What's the best and safest method to do so?
Also, what should I use to apply it? I though I heard that using your finger would not be a good idea because of the greese from you own hands getting in there and causing problems. If so, what should I use in applying it?
4) The CPU is a Willamette P4. I heard that for any CPU, putting on the heatsink can be the most difficult part (<A HREF="http://www.hardwaretech.info/tutorials/system_assembly.php" target="_new">see here</A> ). How do I go about positioning it on the CPU? If I place it on the CPU, but don't quite position it right, can I still pick it back up and reposition it? Or do I need to do clean off the thermal paste from the heatsink and/or reapply the thermal paste to the CPU? Are they any precautions that I should take when locking the heatsink in place? Do you have any other suggesetions for this process?

Thank you for your help in advance,
Kevin

1) No, not if you're carefull
2) If you keep the thermal pad oriented to it's original position on the sink, the material should go back into place just as it was originally
3) Ues the thermal pad
4) The Williamette was initially available in Socket 423, and later in Socket 478. Attaching the cooler would depend on which it is. The Intel cooler for Socket 478 is easy to install but a bit difficult to remove, I unlatch the top and use a pocket knife to pry the legs away from their engaging points.

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