Hi @symeonmattes,
- Yes, the boards are primarily for prototyping. They provide common sensors, connectivity etc in addition to the MCU. If you move a design to production then you would start to identify the elements on the board that you need to keep in order to build a smaller (and usually cheaper) unit.
- Yes, you should be able to extend boards beyond their built-in features. The kit you are looking at actually comes in two parts - the Agora board itself (with the sensors) and the Fidor carrier board which handles debug and power. The carrier board should allow very straightforward additions to the overall kit.
I think @gldelta may be able to provide some further info on the Agora kit.