Can multiple users access ArcGIS styles on server at same time or only one?

Running ArcGIS 10.0 in our environment.

I created a styles db and saved it on the server. Can multiple users access the styles at the same time or only one?

Second, after experimenting I can add the style with the Style Manager and then click on "Set as Default List" and I think that will make it so that any new map created will reference the styles by default, or is it only for that map?

I don't quite understand how the styles are referenced. Is it per map or per ArcMap session?