Seriously, read the interactive guide here on this site and the beginners guide at steam, it will make the game much more enjoyable for you.
http://steamcommunity.com/sharedfiles/filedetails/?id=307389079
Short answers:
Depot placement doesn´t really matter, other than how long your trains and trucks/buses need from there to their line. You only use depots for buyinfg new and swapping old vehicles.
Connect all zones witch each other and the train station. By coach, bus or tram.
Your services will only be used if: the alternative takes longer than your services, and if your service doesn´t take longer than 20 minutes to reach the desired destination of the passenger/freight(not sure about the freight).
