When making an imposition layout, is it possible to stack multiple orders side by side instead of 1 card up on the whole sheet?

The imposition we have built into eDocBuilder is just for that one particular template, so you can not impose multiple jobs. You can create an imposition scheme for a bc template and let the customer upload a database file into the template that produces multiple bc's and have them all fall onto one sheet. 

The other option is to look into our Automated Workflow Integrator (AWI) that will pull order files out of Pressero, into a hot folder that you may have imposition software set up on. You can learn more about this option on our website: http://www.pressero.com/page/web-to-print-automated-imposition-workflow-example