I suggest you use open hardware monitor. It shows you every temperature of your computer (CPU, GPU, motherboard, etc.)

Set the maximum processor state to 90 or 95% and you will see your CPU stays at 2-2.3 ghz.

I suggest you request for RMA as soon as possible.

I would not recommend you to wait for the microsoft store. Even if it becomes available, the price will most likely be much higher ($200 higher I assume). I don't know how much your gift card worths but i still recommend to buy it from asus retailer ...

The temperature on your laptop is fine. My G550JK (3 weeks old) is experiencing the same temperature. When you plug in to play games, the power option automatically switches to power4gear high performance and push the CPU speed to the max (~3.4ghz), ...