How do you export .adf in ARIS Express to regular ARIS applications?
Look at File > Import in your Business Architect. There is an import command for *.ADF files. This does the trick :-)
After the import you will have to consolidate your objects in the database, since AE doesn't know definitions and occurences. The easiest way IMHO is to search for "Objects with identical names" in the Find dialog and start the consolidation there (right click on a line in the search results).
The latest version runs on 64 bit and the only thing I am aware of that might make trouble is the Java files needed for sync with SolMan - you have to take care that you grab the 64 bit version.
However, Global Support/your Account Executive might have more insight and detailed info for you.