Sorry, Some items are coming soon. See some postings of documentation see here
Here is a list of icons and their meaning
NO! The system sends an email to your customers. Up to you to follow up and collect your money. TapTime only bills you one credit when you generate an invoice. If you do not have credits then it just creates a watermark advertising. So free to use, one credit to generate invoice, or free if you don't mind a watermark.