There are guardrails to maintain the personalities of the characters and basics of the story, but it can be altered permanently in some cases.
Sure thing. The whole thing is set up to maintain episodes and characters like a tv show would. Changes can happen as it goes on, and there can be alterations that are permanent changes, but generally everything gets back to normal at the end of the episode so they can all come back for the next one. Tell it to change a wall color or put someone in a robot costume and it will (usually), but whether that sticks around depends on the story that develops.