Congratulations, fellow trouble-shooter! My wishes of happiness and peace to you and your family.
1. According to what I found on the
Dell BIOS download page, the instructions to follow are quite simple. You shouldn't have any trouble there at all, especially since it's your field of expertise. Keep however in mind that you should update the BIOS
before you install the new CPU, to ensure no compatibility issues arise.
2. Yes. I suppose your actual cooler may not be up to the task if it's the stock one, so you'll have to acquire another, given that the seller in question doesn't ship one with the X4 955.
3. As you can see, it's physically
possible to install the AM3 CPU on a AM2+ motherboard, as the former model was designed with 2 less pins that don't affect its compatibility with the latter socket.
All you
should do to ensure compatibility, is update your motherboard BIOS. While this may not be mandatory, it's predominantly suggested where I have thus far read about this line of upgrade. Otherwise, you're good to go!
JD