I am posting each of my suggestions separately. I realise that makes a large number of posts, but it ensures that no suggestion gets lost if there are a lot of comments.
Suggestion 13: A three hero limit seems somewhat miserly. I suggest that each town be allowed a junior hero (the ruler of the local castle) plus the current three heroes (who could be considered knight errants or something) who can be at any level. Perhaps the local hero (who can never be stationed elsewhere unless there is a replacement) can be allowed to be at the intermediate or senior level depending on a suitable town hall and barracks level (for example, 12 each for intermediate, 16 for a senior hero).