First as far as idle temps, i would say that could be a bit high, 33c mmm not bad, 35c bit high. But the real test in a cooler is not at all in idle temps, it is under full load that matters. And yes if plugged into your mobo DO NOT have any fan speed control enabled or on auto disable them, you want your pump running full. As far as a push pull that is the best way, but it also depends on what fans you are useing and whether you are useing it as sucking air in the case or out, i always set theses up as blowing out, if you have a top 120 vent in your case try that-that is were i get my best temps.
As far as the tim that is preapplied to the cold plate-it is some of the best there is, so if your getting good temps and are ok with it, no reason to change it,remember it may be some of the best there is but, how it is applied can ALWAYS make a big difference no matter how good it is.
I still use AS5, but there are about 4 others that get as good and maybe 1-2c better includeing the shin-etsu,mx-3 or 4 is great too.
I always clean the surfaces very well and let dry for about 15-20 minutes, then i tint the CPU and tint the heat sink, than apply a very small rice grain size dot to the middle of the cpu. I never use what is preapplied, but that is just me.
BY the way i always lap both cpu and cold plate also.