Glad to hear that you’ve already made it through the initial sync and are able to start utilizing Method.
As for invoices, they are not currently based on sales orders nor estimates; however, with a little customization, you certainly could configure your Method account to reference invoices on sales orders and/or estimates. Same thing with the Purchase Orders and receiving items reflected on PO’s. As it stands, Method’s Customer Center, Vendor Center and Employee Center are purposely designed to be very basic templates, so that allows you as the end user to easily customize these templates with ease.
Please note that we will have documentation on customizing Method posted to the website in the near future. Likewise, we already have a MethodCRM User Guide online already. Here is the link to the documentation page that contains the CRM documentation as well as other self-service documentation: https://www.methodintegration.com/web/self-service-documentation.aspx
Also don't forget that for a limited time we're offering a 30% discount on all customization packages should you decide you'd prefer to have us do the customization work for you.