This is all fine... and if truly stable, a good overclock.
Yes, the gpu probably has more juice in it that can be extracted. Use something like msi afterburner and push your clock incrementally wile testing it in between with something like 3dmark vantage/11/firestrike
Good luck, post back if anything interesting occurs
Every cpu is different. For Ivy bridge the tjmax temp it is 105c yes. Thats the highest temperature the processor can hit (give or take 3c) before it will start throttling down to cool itself and avoid damage. It has been tested and observed that the cpu shuts down completely at 120-130°C to avoid permanent damage.
Its just people are often more cautious and like to go lower on the temps than intels own specifications and guarantees. And its probably right to do so especially if you're overclocking... just to make sure you don't kill your cpu early.
So safe temps would be up to 90 - 95 in my book, which most likely you wouldn't hit on a nice cooler anyway. Its just lower temps can help with stability overall...