How is at the moment the most recommended/best (and preferraby free) way
to connect to Firebird from Delphi 6 and Delphi 7? Also would be nice if
it worked with Kylix and would be compatible with future releases of
Delphi and Firebird.

At the moment with Delphi 6 Enterprise I am using IBX but as I
understand IBX and FB are becoming more and more incompatible. Also I
understand that from Borland there will be no components/support for FB.
What should be used instead?

On ibphoenix.com there are several possibilities: FreeIBcomponents,
IBObjects (not free?) etc. etc.
Also I downloaded IBPhoenix ODBC driver. If trying this with Delphi 6
ADO components when opening ADODataSet gives error message "Unspecified
error". But it workes fine with BDE components through ODBC data source.

What about dbExpress drivers for FB?

Thanks.