Hello Juergen.
About point (a) I also had that problem... Couldn't figure until now how to correct that. Now about (c) do you face that situation on the development machine or in a client machine? I did some tests... Created a table with two columns, a numeric & a varchar! Inserted a row. Created a small application to test it on runtime (at the development machine). So for me when the app starts it connects (using firebird ado.net), and retrieves the datawindow!
I don't know what I'm doing different... Except some options in the transaction object...
// Profile FirebirdTest
SQLCA.DBMS = "ADO.Net"
SQLCA.LogPass = <*****>
SQLCA.LogId = username
SQLCA.AutoCommit = False
SQLCA.DBParm = "Namespace='FirebirdSql.Data.FirebirdClient',Database='FirebirdTest',PROVIDERSTRING='Database=D:\\Data\\FIREBIRDTEST.FDB;DataSource=localhost;Port=3050;'"
This one is used also in the application (exe).
Also FirebirdSql.Data.FirebirdClient isn't in my references for the application. I mention that because it was one of my previous questions.
Andreas.