You can easily import any Build Service repository by just providing the name in the 'add repository' section using the 'import repository' link on the right. Would a Build Service browsing be more useful there?
Yeah ... I see what you are thinking of.
This is currently not planned, no. The two services should complement each other (that's why adding with an obs project name works), but still be somewhat independent.
If it's due having some packages that you don't want to share: This feature is planned for the future.