Can't help with the gurgling but I had the same problem with a sedra on my Euro-reef skimmer,,,, I got one of those cheap white plastic kitchen cutting boards from Walmart and put it underneath the skimmer in the sump,, that seemed to dampen the noise pretty well.
I raised my off the sump floor with a plastic mat and the vibrations are gone. To lessen the sucking sound, go buy a longer airline tubing or a long, thicker tubing that will slide over the exisiting airline tubing. It'll muffle the sound. Just make sure to check the tubing every month or so to make sure no clogs have developed in the long run.