(3) You don't need LayerNorm for Time-mix. In fact, the model converges faster when LayerNorm is removed.
Moreover we multiply the final output of Time-mix layer by γ(t). The reason for the α β γ factors, is because the context size is smaller when t is small, and this can be compensated using the α β γ factors.
* The Channel-mix is similar to GeGLU (https://arxiv.org/abs/2002.05202) with an extra R factor.