My advice is that CMS plugin features are self contained and don't depend on other features nor try to orchestrate other CMS features. A content feature should not know or care about what other features are on the page.
If you build a custom event calendar then you should build into it the ability to do whatever you need as far as predefined events.
There are sub systems which can be re-used by different features such as content rating, content history, and in the future we will have sub systems for tagging and comments, but I differentiate sub systems which are intended to be re-used across features vs content features which should not have cross talk or dependencies with other content features. Any feature that plugs into the content plugin system is a content feature.