Hey @Macey_Cherry ,
When you setup something like this, you start with setting up a good data structure.
Generally speaking, it helps if you share a dummy doc that resembles what you are trying to build. At this point, don’t worry about relations, sorting, pages, etc.
You are saying that your tasks and departments are spread out in different pages, but a task is a task and a department is a department, the data lives in a table and a table can have different views for different purposes and be shown on different pages (but it stays one table).
One view might show the tasks for a department, another page might show the tasks for a person, and yet another page might show all tasks due at certain dates.
When you work with views, each view always shows any update, regardless of the view in which the change was made.
Start with your base tables (one table for the departments, one table for the department managers, one table for the tasks).
Keep it (initially) as simple as possible. The beauty of Coda is that you can change just about everything later on while keeping your existing data.
Depending on how you want your team to use your doc, you might only need a couple of pages: if your users apply filters (which you, as a maker, set up for them), the same table can be customized to show only the tasks or departments for which this user is responsible - and when they log in the next day, the filters are still set for each user.
Many of us are willing to help, but we need a little more to start with (at least, I do - I can’t talk for other people 
)
Greetings,
Joost