Is there a way to automatically load libraries, change to a certain working directory, etc. when launching Dymola?
In recent years there are two options that might help you.
File>Library Management>Install This dialog allows you to open a zip-file or something similar of a distributed library, install it, update MODELICAPATH to find it again, and even update the File>Libraries menu to include it for future use. All in one operation.
Simulation>Edit startup.mos If you prefer to edit the startup script, this is the convenient way to find it end open it for editing.