1. In some cases, yes. In most cases, no. Look here:
http://www.flyertalk.com/forum/briti...l#post27687629
2. BA, AA and IB only. Look here:
http://www.flyertalk.com/forum/briti...l#post27691539
3. Ummm, sometimes? AFAIK at least one BA segment is required. If you have no BA segments, the app would be useless to you anyway?