You may want to review past threads about discussion lists.
The short answer is that many of the issues you raise are known issues, and are being worked on. At this point, the newer version of Mailman is out of beta, and we’re working on getting it setup to work with our system.
Adding a list does give you a chance to add a shorter alias for the list; and this alias will work - however the address given by Mailman will still be the longer one.
I’m not sure that this warrants a category of its own, though… I don’t think that high a percentage of customers (overall) even uses this feature.