My questions regarding over clocking my FX-4170

First off the reason for the overclock is I didn't have much money when I built my PC but then got just enough for a new video card and now I feel it is the CPU letting the team down plus overclocking is cool.

My specs are as follows:

FX-4170 H-70 to keep things cool ASrock 970 extreme 3 8gig(2x4g) of the AMD ram- 1600 I think Antec 550W PSU Gigabyte 7970 OC WD Green HD

Ok so I read a ton of guides on overclocking and gave it a go. Given the unlocked multiplier on my cpu I have used that so far to get the increased gigas. At the moment it is sitting at 4.5Ghz and I have set all the voltages to the default ones manually in the bios but got some rounding errors in prime64 so I bumped the CPU core and NB voltages up a 2 ticks and it all seems gravy. And now comes what I have been wondering:

1. Why are some of the cores slower than others.

2. At my current OC the times for hyper pi have gotten slower on average though 2 of the core have gotten faster and some are substantial slower

3. Should I change the CPU frequency (the 200Mhz one) or just the multiplier

4. what are the max voltages I can use for Vcore, CPU NB, NB or how can I tell they are too high or low.

5. In the AVP benchmark the FPS went down when I added this overclock (~1-2 FPS)

6. why is the voltage reported from the AS rock tuner different to what I set in the Bios

7. if I just use the multiplier do I need to play with the ram

And thats it for now I think: look forward to seeing what you guys think.