I have an application written in D7, Firebird 1.5.2 classic is the
back end. I used the Interbase components (IBSQL, IBQuery, etc) that
were native to Delphi to connect to the database.

Would it be feasible to upgrade to Firebird 2.0 with this
application, or will I need to rewrite it?

If I have to rewrite, what is recommended? ADO?

most of my queries and sprocs are fairly simple, the only thing even
remotely sophisticated is the application uses some of the Interbase
Administrative tools to maintain the database. Also, I'm using the
IBEventNotify.

For the curious, I need to go to .NET because the client wants to put
a web frontend along side the app.