OC G0 Q6600 to 3.2GHz - Temperature readings (+some more questions)

Hello, I built my computer a good few years ago now, but for whatever reason (probably as i have my finals coming up) I have decided to overclock my processor from stock speeds - this is my first time overclocking.

Anyway, my first change was to set FSB to 355 x 9, I set vCore to 1.3000, RAM timings to 4-4-4-12 at 1:1, 2V.

I am currently stress testing with prime95 (2 hours in), and everything seems to be okay. I am using 4 programs to monitor temperature (!) and they are all giving different readings (speedfan and everest are ~10 degrees lower than Hardware Monitor and CoreTemp) so i have a few questions:

1) Why are the temperatures different / which one seems closest to the true value? (see image)
2) Do these load temperatures seem alright?
3) Why is the core voltage shown as 1.256V in CPU-Z, and is this the actual voltage going to the CPU rather than the bios setting?
4) I am happy with the performance from 3.2GHz, so after I find this stable, should I decrease the vcore and test again (to get lower temps)?
5) Is it safe to enable the setting in BIOS, CI5 (cant remember the name, but it reduces the FSB multiplier when not under load)?

Thanks a lot!  

System:

Q6600 G0 Stepping
Arctic Freezer 7 Pro Cooler
Asus P5Q-E
Patriot 4GB (2x2GB) Extreme Performance PC2-6400C4 800MHz DDR2 Dual Channel Kit
HIS Radeon HD5770 1GB GPU (Used to run 8800GTX until it broke, so this is the newest component)
Samsung F1 1TB HDD
Tagan 1000W PSU (cant remember model number)
Lian Li V1000 Case
Windows 7 Ultimate 64 Bit



EDIT: sorry the Everest temps weren't displayed but they are 52 50 49 49 for core 1 2 3 4