Hi Dan
I’ve been using Agenda for a couple of years. I find it really powerful for the core notetaking functionality. But it’s not and doesn’t claim to be a fully fledged task manager.
I prefer to keep things simple, and I’ve tried various ways of managing my tasks - within Agenda or outside in parallel!
The approach I’ve been using for a while is to use tags (#priority #soon #sometime) for items I need to do within notes (an evolution of The Time Sector Method](The Time Sector Method). For recurring tasks I use Reminders, and set Agenda so those reminders appear in the calendar pane.