A Whats App broadcast list can only contain up to 256 contacts.
Recipients must have their phone number saved in their contacts to receive the broadcast. Else they won't be able to see the clickable link in the message.
Charges for conversations are based on the user’s country code.
The charges will be different, depending on who initiated the conversation (the business or the end-user).
A significant amount will be charged if the user replies after sending a message on Whats App.
You can't use the same content and same language for more than 1 template. To avoid this you need to use different content or different language and different names as well.