For expressing the glands you can use a exam glove and use some lubrication on your index finger. This can be passed just inside the anus where you will be able to feel the anal sac around 7-8 oclock (look at the anus like a clock) and 4-5 o' clock. From here, you can massage the fluid out of the holes that sit around 3 and 9 o clock. This does take some practice so don't get frustrated. You can do this under the supervision of your vet the first few times.
As for the dental cleaning, this is porbably a good idea. Having this done at UC davis is a good idea. They will have a anesthesiologist and cardiologist available if there is a problem with the heart. PLus, they will be able to evaluate the heart and determine what is causing the murmur. One recommendation that is a good idea is to start antibiotics a couple days before the dental procedure. This will lessen the likelihood of immobilizing bacteria from the mouth into the bloodstream which could cause an infection in the heart. Overall, if this murmur is not too severe, I think she will handle this without an issue. I hope this helps and gives you direction.