[X] Have Gengar phase through the door and unlock it from the other side. If this isn't possible have him phase into the door to either unlock it by manipulating the locking mechanism or read the answers to the locking mechanism from the inside.
[X] Seek out the Language - Taking some pictures of the unknown script and returning to the Pokecenter will allow you to decode it somewhat easily. But it's possible that this leads to a riddle that's hard to solve.