The 750i wasn't a good board for overclocking quads, do you have the latest bios?
The TjMax is 100°C for that cpu.
If you are not raising the vcore enough then your pc will not boot due to lack of voltage. You're pretty safe up to 1.3625v with decent cooling. Are you overclocking the memory as well or using a divider and keeping it at DDR2 800?
PC Wizard is probably not reading your chip correctly because it was written before the cpu was released, I wouldn't worry about it.
Does the cpu MHz read correctly in cpuz, Real Temp, Core Temp etc?
Variance of temperature between cores is normal, sometimes there can be up to 10°C difference, it just depends on the chip.
(not card) temps are dependent on the cpu cooler you have, which one are you using?
The core sensors are not designed to show idle temps, they're there to monitor load temps and start throttling in case of a thermal event.
You need the later versions of Core Temp (0.99.3) and Real Temp (2.79.8 beta) to get the correct TjMax as the TjMax for 45nm has only recently been released on the Intel Developers Forum and incorporated into the latest versions of monitoring software.
The difference in voltage between the bios and Windows is called vdrop, the difference in voltage between idle and load is called vdroop, all boards do this to a degree, some more than others, I'm not familiar with your bios, is there a setting called Load Line Calibration or similar? If there is it is designed to lessen vdroop when enabled.
Your memory is programmed to the JEDEC standard of 5-6-6-18 at 1.8 vDIMM but has a performance profile of 5-4-4-15 at 2.0 vDIMM if your board supports the use of EPP (Enhanced Performance Profile)
You don't need to disable Speedstep, C1E or EIST to overclock either btw.
Off topic, if your name is Dan why is your user name Jennifer4u, identity crisis much?