Hello -
Yes, you can import orders from a DSN. One of the panel in the import wizard will ask if you want to "Use a Data Source Name (DSN)"
It is generally not a good idea to read or write to the project data tables directly. There are integrity rules to be maintained, BLOB field data, etc. Best is to use the API to read or write ArcLogistics data since it will take care of these things. Using the API to import or export data is usually the best way to make it seamless to the person operating the software.
Jeff