To make sure that the duchy of Feann is economically stable it is going to be essential to ensure that masters of certain arts or trades teach younger people how to do them. For this reason, it would be a good idea to have a school system or some proper training scheme in place where young people can attend lessons to learn new skills.
Priority in training will be given to services that are most needed by the duchy. For instance, if the duchy is trying to build up a naval force, then shipbuilding will be given a little bit of an extra boost when it comes to training. Having said that though it is also essential not to prioritise one task excessively since it could end up at the stage where the duchy has too many shipbuilders and not enough of other trades or skills. Once we have a stable base of skilled tradesmen, then education will probably settle down and continue at a steady rate giving people more opportunity to decide what they want to do with their time. At the start, though it is likely that everyone will be required to help make the duchy a success for everyone but the initial chaos should calm down after a couple of weeks of real world time.
Education will be funded by the Duke up to a certain base level, and then any extra training that people want to take above a certain level will cost them money. Again depending on duchy need the amount of free education given at any particular time might change.