Yes, most provide hairdryers and the shampoo is a combo shampoo and conditioner in a dispenser in the shower. If you don't mind those, they are fine, I just bring smaller sizes of what I usually use. The hairdryers are fine, but if you have longer thicker hair, may take awhile...I have no problems with them.
You can purchase a soda package on Princess, i dont' know what the current prices are. On Princess you are allowed to bring aboard a reasonable amount ofwine/champagne, but if you want to drink it at dinner you will pay a corking fee, all the info is on their web site