Start with the back course, yes it can be used in a departure. Some SID's (Standard Instrument Departure) will require you to track the back course after takeoff before executing a turn.
Apart from that the back course can be used as an approach as well, as far as I know it can only be used in the USA, but I may be wrong.
As for how far out the ILS can be used to line the aicraft up is based on the coverage of the localiser beam. The localiser lines the aircraft up, and the glideslope descends the aircraft. The coverage of the localiser is 25nm (18nm in USA). However in a real world situation you will normally not line up until at 10-15nm depending on the approach.