SQL CE implementation

Question

I have a small Windows application and am trying to use SQL CE for local data storage. I had some problems with its deployment. I am using ClickOnce deployment.

First question: In the properties of the publication → Application files that I installed in the data file (Auto), Required, Include. However, it seems it is not included? When am I in the place where Click Once installs on it?

Secondly: Click once, creating a new directory in the User \ Local \ Apps directory, with application files and an sdf file (I hope!). When I update the application and release a new version, I do not want to start from a new database ... will all data in the existing database be lost? It just doesn't seem to make sense? What is the procedure around this?

thanks Steve