Since the $99.00 seven day ticket is your day pass, you can add the HHN ticket for which ever night you want to go for as little as $29.99...it's called the Stay & Scream upgrade. You would be allowed to stay in the park after closing and get a jump on the houses. Most of us regulars do S & S since you could end up spending the majority of the night outside in the line if you aren't there early.
A follow up question: So if we have a season pass, we can buy the stay and scream ticket at the park ticket window on the day of the event?
If this is the case, it is a better deal than the Florida resident rate. It is confusing on the HHN website. It says To purchase your Stay and Scream upgrade online, you must purchase an additional daytime admission ticket to Universal Studios or Islands of Adventure.
That sounded to me like you have to purchase a new daytime ticket. It doesnt say you can just purchase the Stay and Scream in the park with an existing day ticket. Another question: Can you purchase the stay and scream and NOT go in to the waiting area, just come back later?
You can buy your S&S ticket the day of the event inside the park. Stay and Scream is just a convenience for people inside the parks, the ticket itself is no different than any other HHN ticket. So yes, you can purchase the ticket and come back later but if you are outside the park when it closes you can't come back in just because you purchased that ticket. You will have to wait outside until they let the regular HHN ticket buyers in.