Are Campagnolo chains typically louder? - Not really.
Are Chorus chains any quieter due to the lack of hollow pins? - Probably not noticeable.
Are some lubes better than others for keeping a drivetrain quieter? - I'm guessing thicker is quieter but also dirtier.
Is a compact crank design louder than a standard crank? - no?
Do Ti frames have a louder signature due to its material density? can't tell you. I'm a carbon guy.
Do all rear derailleurs from the same company in the same model sound the same regarding noiselevels? - I heard the SRAM RD's created a little bit of noise, can't remember where I heard that.
Can some wheels magnify drivetrain noise levels more than others? - no
I've had great luck with the standard KMC chains (performance / nashbar) in my full Record setup. Campagnolo can be more finicky than Shimano which may lead to more noise if not tuned properly but my setup is dead quiet when lubed properly.