SCC and/or DBMS?

[Wyck]

I'm setting up our group to use the sparks tool and am thinking about creating the sql store so that we can have a shared model.  

If I understand things correctly, having the model in the DB means anyone working in will immediately see the changes anyone else makes.  

My question are as follows:

1) Does the shared model also give us Versioning capability?  

2) Is it possible to lock out an area you're in the process of making changes to so that the developers don't step on each other?

3) Does using the DB Store mean that we don't worry about integrating to an SCC?

Thanks,
Alex