If the wires get close to the right location, you can put new wall plates on and run external wire from there to your speakers. It saves you the trouble of running wire across the room and through walls...which you don't have time for with twins coming!
And yes, you should be able to ignore the ground wire for your speakers. If things work with just the two wires, you're good to go.
And yes, you should be able to ignore the ground wire for your speakers. If things work with just the two wires, you're good to go.