I can use the P&L or Income Statement reports to see expenses for a month, but it doesn't include the mortgage payment since I set this up as another account, rather than just an expense. I'd like to know how I can see a report of all payments together.
You can edit the the parameters of the report including which accounts are included.
When viewing your report click the 'Options' button on the toolbar and then go to the 'Accounts' tab of the options dialog.
After the report does what you want you can save the report with a name. Then the next time you want to use this report use the 'Reports>Saved Report Configurations' menu choice and then choose your saved report.