My new baby girl will be here next week
Cosmo was neutered last week and is already starting to act more calm and his bald spot has even gotten smaller. I'm so excited to introduce them... after thirty days!

What should I watch for during the quarantine process? Will parasites be evident even before the last fecal test, are there symptoms?
She is coming from a very trusted and knowledgeable breeder, so I'm not expecting any problems. But I would like to know what kinds of things to watch for that might be symptoms of an illness.

Also, do they usually try to bark and communicate through the cages? Will there be any signs that they will get along?

An initial check up and fecal test is done at the beginning of the quarantine. The reason you wait 30 days and do a SECOND check up is so, if there were any parasites, they will show up in the second test, even if they didn't in the first, given how parasites can take a while to hatch.

During that period is better to keep the cages far away from each other, if at all possible in another room. Gliders can usually sense if there is something different in the house, and so they may start barking, they may not; depends on the glider. The most important thing is that, during this period, you have to make sure that the 2 gliders nor anything they've touched comes into contact. So, you need to clean everything you can between play times (yes, you need to have separate play times), so no diseases are transmitted between them.

After the 30 days, and if the second check up shows everything is ok with the new glider, there should not be concern of transmission, and you can start the introduction process. Below are a few introduction methods:

www.sugarglider.com/gliderpedia/index.asp?Introductions

Hope this helps.

Usually sugar gliders (as I believe majority of animals) mask their illnesses, so it may be not noticeable until she/he is very sick, signs could be: lethargy, low activity, poor eating, let me say now, that these signs can also be exhibited when you first bring a glider home because they're stressed, scared and it can take a while to adjust or acclimate. So if the first few days you see the previous stated symptoms, don't be alarmed.

The good news for you, is most likely there will be no parasites, but a fecal check is still strongly advisable.