Hi Dracula!
the answere to your questions:
1. its usual to build a hollow-block for a room.
but its not a "must"

2. the collision dummy is used for the hand.
Its only a liitle block for the collision detection
between hand and insect.
Maybe i will creat a count for points and some levels and so on. But its also free for you to add some new functions.
Have fun with it!
cheers
marcel