1- The temps are normal, obviously better that the stock cooler
2- The TX3 is a basic cooler but can do a good job with your CPU and OC, the only think that u can't wait is hit the 4GHz or more with good temps.
3- Of course that u can, go to your BIOS rise the CPU multiplier, the NB frequency until 3000 and set the HT to 2000 with that u can get good results. Keep on eye in your temps for be sure that all is good.
The amount that u applied make think that could be a problem, you only need a little amount to cover the CPU, this can be applied with a credit card or something like that, DON'T touch the CPU or Cooler with ur fingers.