does this headset mic pair with speaker

Yes, the headset mic pair with the speaker. It is paired already before ship to the users.

So when you turn on the microphone and speaker, it will pair automatically.

Sound distance on the amplifiers?

WinBridge Voice Amplifier sound distance between the microphone and speaker around 15-30 meter. May I know where you will use the voice Amplifier? so I can give you professional suggestions.