I've responded to your question about converting data in another thread. There are a lot of parallels between OJS and OMP, though -- roughly speaking, the articles and article_settings tables in OJS correspond to monographs and monograph_settings in OMP. Many tables are shared directly between the two applications (those described in lib/pkp/xml/schema) and won't need any conversions. The tables you'll need to convert are described in dbscripts/xml/omp_schema.xml (for OMP) and dbscripts/xml/ojs_schema.xml (for OJS). If you have specific questions, let me know and perhaps we can use this as an opportunity to better document the XML files.
Public Knowledge Project Team