Hi Owleyes,
I have been given the following information in answer to your questions and I'm sure other travellers may comment too...
Hairdryers are in all the hotels and pool towels are available poolside.
There is a strict dress code at the Grand Palace in Bangkok as follows: Full length trousers or skirts below the knee, covered shoulders eg top with sleeves, a scarf or pashmina is not enough, nothing is mentioned about see-through sleeves but see-through tops are definitely a no-no, the dress code is to show respect to the King. Other temples are not quite so strict but covered knees and covered shoulders are the usual in all temples and of course shoes off in the temples.
I hope this helps,
Kindest regards,
Julia