Unsure of bathroom materials
The others seemed to have covered your wall concerns, but I'd like to chime in on the drop ceiling. I'm not a big fan of drop ceilings used in bathrooms in general, but if the bathroom is VERY well vented AND the tiles used are SPECIFICALLY for moisture and humidity intense applications, they are acceptible. But you must make sure that they are using the special tiles. Its worth looking into, because the special tiles are like 5 X more expensive than the regular ones and sometimes people try to skimp. Armstrong for example makes a sag resistant moisture resistant panel and also a mold and mildew resisitant one.