If you were leaking this much oil from the upper timing cover, the engine compartment would be absolutely drenched in oil. These covers are a common source of leakage, but it is a VERY minor leak.
Yes, you could wiggle the valves if the guides are that bad. I guess it goes without saying that the piston in that cylinder should be at the top when you do this so that you don't lose the valve into the cylinder.
The seals should take NO time to seal.