Correct! Opposite is when two things face each other, and in front of is when an object is ahead of another, back to front, i.e. I am in front of my friend when my back is to his front and I am opposite my friend when we are facing one another.

1. This sentence is not correct. When we say we are in front of the computer, it means that we are facing the computer (and the implied meaning is that we are using the computer). For example, "I wish my son would have a more active lifestyle. He's in front of the computer practically all day. He never seems to play football any more." For the situation you describe (with your back to the computer), we don't have an exact expression; we would just say, "I am standing near the computer." 2) You can say "I am opposite him", but we would more commonly say "I am facing him". You have written: "I believe "in front of" is used that looking at different directions and "opposite" looking at the same direction." No, this isn't what these two terms mean. "In front of" means near the front of something, as in "I was standing just in front of the supermarket." (I was standing in front of the building, on the same side of the street.) "Opposite" means across from something, as in "The McDonalds is just opposite Pizza Hut on Oxford Street." (The two restaurants are on opposite sides of the street from each other.)