Printing or emailing your invoices should be easier than that, if you open Express Invoice and go to View > Invoices and then click to select the invoice you wish to print or email and then select either option from the icon's menu at the top of the Window. You can also use the option Save to save the invoice directly as .pdf file to your computer.
Regarding the Web access feature keep in mind that your Router needs to have the ports open so you can access the program remotely. Also, the computer where the program is installed needs to be on, and the program running.