you can definitely do the timing yourself, it takes no more than 5 minutes with two people (one person turning the dizzy the other checking the timing)
for knock, you'll hear it most likely.. is your knock sensor throwing code 52 [i think]? a blown head gasket would give you tons of white smoke out of your exhaust.. also for a bhg, if you looking inside your radiator, if its foamy, it either has rabies or a bhg.