Using a monospace font has historic reasons. Nearly every IRC client uses a monospace font as default. It's by the way the system's monospace font and not part of the app.
About the ongoing notification. From my point of view this is the correct behavior as the app is running a sticky background service that eats significant battery and cpu cycles. As soon as there's no active ongoing connection the notification will be removed.
That's also how I understand the Android design guidelines (bottom):
Best regards,
Sebastian