Staged readings are pared down...treat it like you would any new work and keep track of any script changes made, etc. Make sure you know what your director wants to accomplish within the two days of rehearsal to ensure everything is ready for the reading. With two days of rehearsal will it actually be staged, or just the actors reading at music stands? Is it a public reading, or an in-house reading? Also, be sure to have binders for the actors as they will not be expected to memorize.
As far as reading stage directions, that depends on the reading. I've done readings where the stage manager has been the stage direction reader. The majority of the readings I've done, however, do have an actor cast for stage directions. If you are the one that will be reading the stage directions find out from the director which directions they want.
Good luck and have a fun time!