You have a bad one as my GL703GS has been spot on. BIOS 307 fixed the trackpad stutter.
For the temperature, raise the rear or place the notebook on a cooling pad. ThrottleStop can help by undervolting the CPU which will reduce temperatures. I have the previous GL703GS; it can spike as high as 95C, however under sustained CPU load it will hold below 80C
Here both Prime95 & CineBench R15 are running CPU is in the mid 70C region, ambient being aprox 25C/26C. Performance us very solid and temperatures fair for the size of the notebook. I use mine mostly for work purpose and it has been great for the last six months, in your position I'd contact ASUS and RMA it.
Q-6