Make an object transparent if you see it from its back
 

Is there any simple and easy way of doing this? Disable/hide an object if you see it from its back??

Try enabling back face culling:

Great, but can I do the same for a "box" instead of "plane"??

and.. would it be possible to render with a certain alpha instead of full transparency?

thank you.

Back face culling works on any model. However, it does not support rendering with transparency.