Hey,
I am about to replace all the hoses on my 89 300E too...
So far, I think you have got all the hoses identified.....
I would personally recommend replacing all of them, 13 years of engine heat will really hinder the hose's ability to completely seal in the air around all the joints and stuff....
Quick question...
Have you replaced your passenger side motor mount? I am thinking about doing this, but I don't have the tools to do it. (Or the guts!

)
How much do you think it would cost in labor only, at an independent shop?