1 - Does that mean that the DDT will generate insert, update and delete procs?
Yes, the current pre-release version of 1.4.1 can generate separete sprocs for INSERTs, UPDATEs, and DELETEs.
2 - If I have existing insert, update and delete procs, can I put their names into the corresponding properties of the BO? If so, what do the signatures of the stored procs need to be to be compatible with the code that you generate?
Yes, you can use your own stored procedures for the business objects by entering the stored procedure names in the properties on the business objects. The parameters the business object is expecting are described within the newest version of the DDT help, which I am posting in the MyAccount are of the website today.
3 - When the DDT provides viewing, will it be possible to edit the code?
No, the DDT will not allow you to edit the code, but you can use the viewable code as a template to create your own stored procedures.