Regarding score, that doesn't really answer the question. I'll update the passive score indicator anyway, but people tend not to notice when that has changed, so I normally provide an extra active score indicator a la Inform/Infocom as a matter of course. Is this permitted?
Regarding multiple messages, TWO does this, so I guess it's okay. If not, the game is crippled, because you can't do any of the interesting background processing that normally takes place in text adventures - things like NPCs moving around or timed events taking place, e.g. "Starts raining", "Getting dark", "You're hungry", "Bomb exploded", "Mine collapsed" and so on.