The bot might not have the permission to send embeds. Try checking for the Embed Links permission! Still can't figure it out? Try going to the support server and ask!
It doesn't. You might have misconfigured the bot's permission on the server. As a matter of fact: Do not give any bot Admin permission. They don't need it.
Currently no. Though, it is planned in the future!
Yes, the source code is available on GitHub.