Timing cover oil leak question

[skillet]

My timing cover is leaking oil at the bottom. Is there supposed to be oil behind the timing cover and what would be the sources, or most common source for a leak? Like, is there a crank seal that fails or what? Or is the oil just woriking it's way from the oil pan? I noticed before the problem began, a high pitched noise from the front of the truck had developed. You could hear the noise around 60 mph and above, but it would stop if I dropped down below 60. I'm trying to figure out how much to take apart to diagnose and fix it and also to decide if it can be done in an apartment parking lot. Thanks very much for any comments.