That oil from the air cleaner is called reversion and usually appears when you change the pipes, drag pipes are the worst for causing reversion and its all about exhaust harmonics...no cure except standard pipes...or some radical breather mods.
No, Evo valve rattle isn't normal. You can expect some valve train "noise" when upgrading a cam, but not a rattle unless you get really radical on the modifications. Mine rattled since 12,000 miles and it took me years and lots of wasted dollars to figure out the problem for taking advice from too many people. Have to get to work and be back Friday, but send me a PM and I'll clue you in.
Always a good idea to freshen-up the top end if you have time and an extra 75.00 ... while you're into it.
I know this post is from 2009, but I still have a rattle in my Evo after replacing lifters, push rods and rocker arms. What caused the rattle in your Evo?
the only thing left is either the rocker shafts are moving in the mounts or your pinion, to breather,to cam gear mesh is off. it can sound like a hammer hitting an anvil if loose. If too tight it can sound like a loud whine.