1) You can type "-.svn\" in the filter edit in the toolbar. You can also add that to the filter edit's dropdown list in the Options dialog.
2) If you load the home screen and expand the "Edit session defaults" node in the treeview, then select "Folder Compare", you can change the defaults used for all launched sessions. Just add ".svn" to the "Name Filters" tab's "Exclude folders" edit.