Hi mcmarto, and welcome to cruise-chat!
Freestyle cruising has several aspects, most notably no set dining times and casual dress/optional formal nights. In all honesty, you will probably find that people will be dressed similarly to those on your Royal Caribbean cruise, assuming it was in the last couple of years. You can dress for formal night if you wish--but will have plenty of dining choices if you don't.
As far as Freestyle Dining, you can choose between several no-fee restaurants and several that impose a fee. The main dining rooms are open from 5:30-ish to 10:00-ish, and you can arrive whenever you wish during that time frame, although you may have a wait at peak times. (The exact hours will be posted in your Freestyle Daily newsletter you get in your cabin.) Other than the two main dining rooms, there is no fee for the Italian restaurant, although I believe you need a reservation. The Shogun Asian Restaurant, Le Bistro, Cagney's Steakhouse, and Teppanyaki Restaurant all charge extra fees. You will need reservations to dine here.
What are your ports of call?