Try searching the forum… All those points are on here…
If your really new checkout my video tutorials to get familier with terminology and basics of automation;
That one’s a but boring but has links to others.
Regards departments your most likely better off using custom ticket tags or states depending on what you need to separate and how you want flow to be. Tags/states are more flexable than departments in allot of cases and can be reported on in similar way if not more finite.