I have a client-server winform app written in c# with data access to SQL
server 2000 via stored procedures. I need to move the app to another
company which don't have SQL server. I will therefore make use of the free MSDE(MS Desktop Engine). I have the following questions:

1. Since MSDE don't have any user interface, what is the simpliest method to manage the database? Please don't ask me to use the pre-defined stored procedures.
2. To make the app more portable in the future, I want to use c# to
establish all tables and stored procedures in MSDE(instead of transfering from SQL server everytime), what is the proper method? Does MSDE have the default databases(like Master and Northwind) and stored procedures so that I can make use of them? However, if I use the default stored-procedure, how if later, I need to use Oracle as the database? The best method is, of course, do everything in c#, is it possible?
3. I am planning to make the client app capable to connect to other kinds of database. I therefore should use connection string instead of using stored procedure(Right?). How can I perform function of T-SQL like @@IDENTITY ?