just back last week from new york on the qm2, the hairdryers are surprisingly powerful, i have really thick hair and worried too but not a problem at all. Inside the ship was just a nice heat, not to hot, not too cold, i think blouses will be just fine, unless you feel the cold mostly? It was our first time also and fantastic! You will love it, we cant wait to go back
The ships are all conditioned and can be quite cool, it is always advisable to take a pashmina or light cardigan.