1. Check your spam filter. What payment gateway are you using? It sends email once the transaction is complete, and that the user is effectively a client.
2. Do you have a screenshot - use Drpl or equivalent please.
3. Use the quote engine, and give the details on the quote template. Ask customer to send the quote #ID along with their payments. Once payment has been received, mark the quote paid. Everything else remain the same (invoice creation/access from dashboard orders or customers area etc..)
4. You need to create a plugin on seotoaster to send the cart amount to Paymate, and also track back response to set the proper cart status when the transaction is complete. So it's not as easy as what are you're trying to do. Check http://developers.seotoaster.com/
out for development documentation, or consider hiring our professional services team to develop it using http://www.seotoaster.com/contact-us.html