You don't have to use Valve Cover Gasket #3, if you don't want to. Use a high temp teflon sealant and apply to the threads on the hex bolts. I would recommend to let it dry overnight. So far, 2 years and my valley is nice and clean. As for the philips screw, replace them with the same length allen type screw with new washers, or purchase a set from Driftmotion.
Other people also uses, washers from NAPA to seal the Hex valley screws.