Re: Thanos and Loki
I kind of doubt Thanos will appear in any level beyond that of the reference of ending cameo. However, that's because I am, personally, skeptical that Thanos is going to be the villain of Avengers 2.
He'll cast a shadow on Thor 2, by way of Loki's presence and punishment ( and likely scenes of interrogation ). However, it would not shock if Thanos doesn't actually appear at all.