How The Key Scenes Could Be Staged
The first key scene, Act 2 Scene 3, is set in the kitchen of Olivia's house. The previous scene was set in the street, which is a completely different place. I think to change from the first to the next you would have to divide the stage by a curtain. Behind it Olivia's kitchen could be already set up and in front of it, the street scene could be staged. The curtain could be a background with perhaps some buildings on it. You wouldn't really need very many props for that scene, so after it the divide curtain could go back, and with different lighting the next scene could be played and it would seem like a completely different place.
I think Act 2 Scene 3 should be staged with a table in the centre of the stage and the drunken rabble sit at it or stand by it.
I think there should be some steps at one side for Malvolio to come down because that will make him higher than the others and that's exactly how he thinks of himself. There could be some props that make it so you can tell it is Olivia's house, for example an expensive looking chair or some flowers around. These things are easy to take away at the end of the scene.
The following scene is set at The Duke's Court. To go from the previous scene to this scene you wouldn't need to change all that much. The table could be left where it is and you could just have tablecloth put on it and some different decorations. There would also probably be a big chair for the Duke to sit in. If the decorations from the previous scene were taken down and...