Concerning the datamodel drop problem: you might have been run in bug #1072 that prevented deletion of packages with registered parameters on the postgresql version. This bug has been fixed recently, so if you have done an upgrade and recreated the database (re-installed acs) it has propably been eliminated.
Btw, for quick testing it's easier to load the datamodel create and drop scripts directly in psql/sqlplus, using i <bla-drop.sql> (that should read backslash-i) / @ <bla-drop.sql>
