Send /start and the bot will let you know everything you need to know.
No, not at the moment, and there are currently no plans to make it so in the future.
You can either report them here on Telegramic, or you can do so on GitHub: https://github.com/tjhorner/CompileBotIssues/issues
There's no donation method, but you can buy executions instead with /getexecutions. Thanks for your support!
Let @bcrypt know.