A: 

Shouldn't you be using the Oracle Driver instead of the Microsoft ODBC driver? Microsoft's driver will require the SQLNet drivers which come with your full client install. There should be an additional ODBC driver available after installing the Oracle ODAC. Go to the Drivers tab of the ODBC Adminstrator and you should see something along the lines of "Oracle in OraClient11g_home1" with a version of 11.something. That's the driver you should make your DSN from. I've only used the 10g ODBC install (which could be minimally installed with a selection of "Instant Client").

HTH

DCookie