Your first round is the sorority's first impression of you. The handbook will say you can wear shorts but I recommend you get a little more dressy. UCF is pretty much the same in terms of recruitment dress code as UF so I pretty much know what they're looking for. You're going to want to stand out so I would wear a cute sundress the first day.
As for round 2,
DO NOT, I repeat
DO NOT, wear a skirt or a dress. This is craft day and many of the sororities will have you sitting on the floor doing a craft. You will probably be nervous enough so the last thing you need is to worry if you're sitting correctly so that no one can see up your skirt/dress. A cute pair of linen capris with a nice shirt would be good during this round.
The third round, a nice sundress would be appropriate. This is UF so a Lily dress would be great to wear this day.
The 4th round (prefs) is when you should dress it up more. A black cocktail dress or something you would wear to a wedding would be good. No gowns!