MQTT Discovery & old

Configuration
1

Hi Guys
I have Mosquitto broker as my MQTT and added all my ( Sonoff - Tasmota ) devices to HA and they work fine.
However, I would like to change and add MQTT Discovery to my system ?

  1. Do I remove the old MQTT lines from my configuration.yaml file & add the new mqtt: discovery : true as per documentation?

  2. Do I remove all my sonoff devices from my configuration.yaml file or can I leave them there?
    If I leave them as is and my new devices will be automatically added?

Some advice to enabling the new MQTT Discovery feature ?

Thanks
.