1 - tilted can be a verb or an adjective, but it's a verb in this case due to its position in the sentence.
2 - No, they have the same meaning.
3 - tilted is used in the past in a passive sentence, tilting is used in an active sentence. This is the reason 'head tilting' is incorrect, because the head is passive. With his head tilted in sentence would be correct, as well.