To simulate a neuron you don't need to necessarily simulate every chemical reaction inside it. We have pretty decent models of how neurons act. While there are serious potential problems with our understanding of the brain (for example, there's evidence that glial cells matter for cognition but we don't really understand what they are doing) , we don't need to examine every chemical reaction to make a good approximation. Yes, that is still a lot of simulating, but that's part of the reason we can't do it now, it isn't a reason we can't do it in the future.

Even if you let the human your simulating modify his own program, it only makes things worse considering he could easily make a mistake. You can take the processes which the brain performs or appears to perform and model them in a computer. You might achieve the same results or better, but its not a human. But thats not the point. I don't want a computer that can only do the things I can do and nothing else, I want one which is good at things I can't do.

I'm confused by the relevance of your statements here compared to what we were discussing earlier in this thread about efficiency. Having a lot of human brain equivalents running much faster than humans will still help out a lot. Since the earlier claim was about using these entities to improve technologies, it should be clear that having them would help a lot. To one somewhat futuristic (and ethically questionable) example, imagine that every desktop had a system that allowed you to either simulate a brain a hundred times a fast as a human or simulate a hundred brains at normal speed, do you not think that such technology would be very helpful?