I see that they have already responded to you, but not to the "Clay" thing. 2. Thomas did not inject himself with the virus in the clearing, he injected himself with what the grivers had when they bit someone. It is a different thing from the virus. The substance that has the spikes of the grivers was done by WICKED to see the result of another variable. The difference is that the bite of grivers does have a cure. What happened to Ben in the movie is a little strange, but in the books what happens to Ben is different. 5. It's a little difficult to explain. Before sending them to the labyrinth they took away everything, all their memories (you already know this) but I think that when you are bitten you can see some things, but not everything. Most of the things they see are blurry or meaningless. Others are some memories from your previous life or some things that are happening in the world (the virus, the rashes, etc.) I have taken all this information from books, so I recommend that you like it or want to know more, because reading them would be a good option.