2.As long as the wattage and BIOS is fine, all FM2 CPUs (most, if not all are APU) will work on a FM2+ motherboard.
3.I have read mixed things. So far, FM2+ is confirmed by AMD for their Steamroller's Kaveri APUs. I have also majorly heard that AM3+ might also continue for the other CPUs for Steamroller.
AMD will support FM2+ and AM3+ as equally as they do now with FM2 and AM3+.
Because of the new FM2+ socket, and old AM3+ socket, the FM2+ might be supported more, who knows?