user data

Hi, Dialog
For BLE specification, how does the user add his data in BLE protocol?
Is there any manual for operating step by step? which project is the best start point? ble_adv, pxp_reporter, peripheral_demo?
1. how to define a new GAP, GATT....?
2. what data type does BLE support?
3. how to create a new task to gather data and send by BLE?
4. how to arrange interrupt if the sensor's data had to be got by timer/bus interrupt?

Where can I get the sample code of IOT sensor kit ? The SDK 1.0.8 might be something lost.