I am planning to play Europa Universalis IV as Austria, which starts off as the HRE Emperor.
The Prince-Electors at the start of the game are Bohemia, Burgundy, Cologne, Mainz, Saxony, Trier, and The Palatinate.
Austria has five diplomacy slots available at the start of the game, and I'm thinking of allying & royal marrying Bohemia, Castille, Hungary, and Poland. That leaves one slot for a Prince-Elector (probably The Palatinate?).
Moving forward, how do I keep the Prince-Electors pleased to keep me on as Emperor?
Is it advisable early on to use more than the five "free" diplomacy slots to ally Prince-Electors, and then get the Diplomacy idea group?
Also – if a member state within the HRE is fully-annexed by a neighbour and I issue "Demand Unlawful Territory", is IA (Imperial Authority) awarded if the demand is accepted? Or do I have to release the member state through war?