help in some tasks of B1UP sap business one

Job ID: 33273950

Budget: $30 – $250 USD

we recently buyed b1up , and i need some help in these tasks:
1. i want to block specific group of business partner from producing an invoice for them , just invoice-recipet document , so i can guarantee that they will pay immedietly
2. i want to send an email to my customer when he have invoices that he didnt pay yet, with an eamil that show all the details of the specific open invoices
3.to block/ popup a message when producing any new invoices for an BP that exceeded his credit limit
4. in invoice document to show a field that contain unpaid down payments
5. how to block specific users from seeing specific fields/ menu