I am not sure I get what you are trying to tell me, quite new arrays, but lets go.
1. So, I should stop the loop when it goes into negative values? I mean, if there is no Array there, it will just stop automatically or should I manually tell the loop to stop IF 0?
2. I almost figured that this kept happening and even if it checked the neighbouring tiles it would only change the value of the currently picked tile. How do I change the value of objects in an indice that is not even active? (still have to get my head arround these expressions). So I should highlight it -> pick all -> loop?
3.The Array has a randomized Instance Variable that selects the frame of the tile.