Telegram API key

Create a Telegram public channel. Create a Telegram BOT via BotFather. Set the bot as administrator in your channel.

For posting to channels, both telegram API and telegram bot API can post to channels .

Yes you can , you have to invite the bot into the group, grab the chat_id of the group and send the message as you are sending a normal message to a private user.

Open the telegram app and search for @BotFather. Click on the start button or send “/start”. Then send “/newbot” message to set up a name and a username. After setting name and username BotFather will give you an API token which is your bot token.