Summer event

Is possible to "work" on the doors, one daily? I just finished the practice mach(door 12), the second door(door 13) gave me 80 gold ore, but I cant do nothing with the door 14 - does she will be available tomorrow and not today?
When I press on the other special doors, some resources appears.....and I have to pay this resources to get the door open?

Its open one door per day, Only reason we got two today is because of yesterdays "trial run" :)

and does I have to pay resources to get special doors open?

Not if you open them on the correct days, its all free if you loggin everyday and open the correct door