How is the temperature inside? Should I plan to wear a sweater or short sleeves?

Short sleeves

Short sleeves should work, if your the type that's cold all the time you may want to wear a thin long sleeved shirt.

Comfortable

I'd say shorts. Temperature is set to make the kids feel comfortable

Tee Short short or long sleeve they keep it comfortable inside, there free coat racks or lockers rentals sm $3- large $5