You must use thermal compound it is critical in obtaining good temperatures for your CPU without it your processor will overheat.
Yes, Top Dog i Shin Etsu ....Check AS5's web site ... it requires a 200 hour cure time.....If I ahd to hold each build for 200 hours before I tuned in the OC's the peeps I was building for would be living at my house.
Arctic silver or similar will probably be slightly better quality and may drop a few degrees but you won't need it.
You can use the provided paste with the CPU cooler that comes boxed with the CPU. However, I've always cleaned that off and used my own TIM and installed the cooler...you'll net a little cooler temps this way.