Bad rings will not cause oil to pool up above the spark plugs. When you removed the plug, the oil filled into the cylinder. It's just the valve cover gasket.
The lifters are a solid bucket type, so there is no adjustment available. I'd recommend an oil change and the use a of a good filter. Some of the crappy ones can inhibit pressure and cause upper end noise.
Since there is very little to no vacuum on acceleration, the noise is not a vacuum leak.
Your fuel pump sounds like it could be a little louder than it should be, however you can faintly feel/hear it. I would keep an eye on it anyway. Some pumps get pretty loud when they're about to fail.