Hi bcoop,
I'm afraid you haven't conceptualized the Theory of Evolution very well.
the end of the chain where we are now,
See? Don't think "chain"... think "bush".
how much time it would take for a mammal to develop an functioning vision system or something like that.
Vision systems were evolving way before mammalia... as were most of the "things like that". They devolop consequently so your question doesn't make sense.
Has mathematical modeling been conducted of the amount of time it would take to generate the human genome?
I don't think so. I think its way to complex and complicated to form a model based on things like mutation rates and generation times n'stuff like you tried to do in the OP (opening post).
But, given that life has been on the Earth for about 3 billion years old and that modern human emerged about 200 thousand years ago, we can figure that it took about 2.9998 billion years for humans to evolve.