1. I have i5 4690k and my idle temps are around 32c without air conditioner but I have Zalman CNPS10x Quiet cooler which is huge so that could be the difference, what cooler you are using ? Thermal paste do adjust itself when heated but it doesn't make a huge difference maybe a degree or two so you might also want to remove your cooler reapply the paste carefully and then reseat the cooler. iGPU is a low powered GPU however adding dedicated GPU will indeed cut off some degrees.
2. ZOTAC is a reputed brand and recently a friend has purchase ZOTAC 970 AMP and he's happy with it. After checking some reviews on Colorful iGAME 970 I say it's also a good card and comes with a large factory overclock. You cannot OC your CPU on H series motherboard but since you have 4690 (non K), your CPU is locked. As far as GPU OC is concerned it's not dependent on motherboard so you're good with it.
3. The only way we get price slash on Maxwell GPUs is when AMD release a worthy product, so far there is nothing from them except rumors and speculations about R9 300 series and that is expected to be released in June so if you want to play TW3 as soon as it's released then you should get a 970 and who knows when price slash will be effective because AMD has to release something really compelling to cut 970's impressive price/performance ratio.
No need for an apology
those questions are not stupid and beside this thread is meant for all sort of system building questions.
