Well, agreed with that, hopefully it becomes available soon. Also, it will be nice ( I think ) that the character has increased health every time we level up.
To start over, you need to clear data of the app, via application menu on your device settings. Make sure you've backed up the .obb file to avoid additional downloads.
Well, probably they follow the glu coin grinding strategy guide available on the forum here. I forgot the link, but it was posted in this forum, check it out.