So I'm probably late here, but if you put blocks like this (preferably glass so you can see through):
You can attack monsters that come to where the corners of the blocks meet from the other side
how do i set my respawn in my cave....
freaken died the first time and couldnt find my way back
You can't change your spawn point in single player Alpha
Edit: My Lava Well is the best way to get rid of useless crap ever, stand in front of it and throw items in, and FWOOSH - it's gone!