Need help to go with nrf52840

I'm a newby in bluethoth communication.
To control model cars and model trains in scale 1:87 I built a decoder with an ATMEL chip.
The communication based on digital infrared data frames.
The decoder helds the startup information within the EEPROM.
Now I want to use bluetooth to communicate with.
My considerations are:
Master and slave communication (may be mesh)
Master sends and reads information to/from slave (polling ?)
Each slave controls the function of the car or train dependend of the received data from master.
Besides communication every slave must be able to analize or built:
Analog input
Digital output
Set lights on or off
Create servo pulse
PWM to lights
Send serial data to a Atmel controller
PWM for motor control
And more to do...
Which examples do I need to have the basics running on the development board?
I've got working the blinky example.
But i dont know which example i have to use to get master and slave communication?
I bought 4 development boards for testing from mouser.