Toyota Repair: Valve Cover Gasket

Question
While hunting for my O2 sensor, I noticed I have oil leaking around the bolts on my valve cover. I understand I need to remove the plastic lid, then the metal valve cover. Do I need special adhesive to attach the new valve cover with?
Also, the car is a 2003 Camry XLE with 100,000 miles on it. I recently asked this site a question on the location of my O2 sensors due to a P0031 code. Could the oil leak have something to do with that code? I also have some blue smoke at start up, but not at any other time. No oil consumption. My question is whether I might have a major engine problem causing the valve cover leak, bad O2 sensor, & blue smoke & how would I know? I purchased the car used 2 years ago at 70,000 miles & immediately switched to synthetic oil.

Answer
Hello, first off all the blue smoke is typically leaking valve stem seals, very common, it can be done without removing the cylinder head. The valve cover gasket is a rubber material and requires no sealer except at the corner areas where a small amount of silicon sealer is used.