Yes, there are hair dryers, but since your DW has loooong hair, I'd suggest she bring her own .
No, there are not irons in the cabins and it's against every cruiseline's rules to bring one. There will be irons in the laundry rooms onboard, or you can send things out to be pressed for a minimal fee.
Please, don't bring an iron! It's very dangerous !
"A truly happy person is one who can enjoy the scenery on a detour."
I'd suggest you take a power strip since there is a serious outlet shortage in your room. You can plug in the hair dryer, your camera charger, your laptop power supply, etc and shut it all down by puliing one plug when you leave your room.