So I can use the same DataSource, Result, Connection objects with SQL server?
Yes - since these are all interfaces. The implementations are provided by the Driver you choose (Microsoft supply one which is fine, but I'd recommend jTDS).
What are the major differences in regards to stored procedures.
The big difference is in Oracle you can use PL/SQL or Java to implement your stored procedures. In SQL Server it is Transact-SQL you use. If you are familiar with PL/SQL, T-SQL is fairly easy to pick up.