To generate the print form, you must send requests to the main infobase using the web service.
You can find an example of the Print form template chapter of Practical developer guide. To generate the barcode you can use the Barcode printing component that is included in Managed application demo.
After the print file is generated, you can either print it on the printer connected to the computer where the main infobase is placed or send it as a result to the mobile device and open it with some external application that supports printing, for example Adobe Acrobat.
The SpreadsheetDocument object now have printing, print preview, and page setup default commands when it is placed on the form in the mobile application.
It also have Print() method and PageSize property that you can use in your mobile application.