Odd problems

[The Rock Worm]

When I go into the game, some of the wall's textures are one-sided. Meaning one side is solid and has the texture I am wanting (in this case, a cavern), but the other side is transparent and I can toss rocks through it. What's worse is: in my story, you awake from having fallen down this shaft; you should only see the inside of the shaft and not see the outside of the shaft (aka I can see the outer edges of the model). How can I fix these?

Another problem is I am uncertain how to add text to a note. In Amnesia, you picked up diary notes and letters, how can I replicate this?