the emperor landing if we look at a six film saga, is like th final showdown. like gandalf said,

Gandalf said:
The Board is set, the Pieces are moving

its cool how we dont see the super badguy properly for 2 films, then hes here right at the last minute in the final act to see off the rebelion.

like you said its 1-1 and the battle could go either way.

The vader scene should be included i guess if you plan it to be part III of a trilogy, as the emperor has had no introduction otherwise. if its part VI then its unneccessary, and potentially a bit of a headache for you.:P