This is an excellent start to what I need. However, I have two additions needed to make this perfect for me and perhaps others. First, I also do "flat fee" billing, a single price for a service. Second, I also offer time payments. So, I need a way to track payments, send out monthly invoices, and so on. What is the best way to address this? I am willing to pay a developer if needed. Do you have videos that already integrate with this? I have not found them but I may not be searching correctly.  Thank you.