I did not fly in Etihad Airways but my roommate did...Yes Etihad Provides hotel accomodation @ Abu Dabhi International Airport if there is a long layover (>~12 hours) but its based on the availability..The best thing to do is contact the airlines as soon as you purchase the ticket so that they can book a room for you. The hotel is inside the Airport and you don't have to worry about Transit Visa.
BTW when are you flying ?
Good Luck.