Andre:
1. I am a hair larger than you and I have a 59cm '06 Buenos Aires. Although the pics are now missing, you can read my review here:
http://www.bikeforums.net/showthread.php?t=344436
Here's what I have to add: I really really love the frame on this bicycle, but the Bontrager stuff is garbage. Specifically, all of the eyelets cracked on my rear wheel around 4,000 miles. This is the drawback of buying a road bike from Trek and Lemond at this price point.
2. You'll have to gauge the differences between carbon/steel and carbon/aluminum for yourself. A test ride should help you decide. The carbon/steel provides a very plush ride coupled with a more aggressive position on the bike which i really like. My Cannondale used to beat me up on any rides over 20 miles. The same rides on my Lemond are silky smooth. I find that on longer rides I'm actually faster on the Lemond because I stay fresher. The steel is also more durable.
3. If you go with the '06, ask them to swap out the triple with a double. That's what I did anyway. If I had to do it over again, I'd offer to pay a bit more to upgrade to a Shimano crank and bottom bracket. The Bontrager crankset is garbage too.
4. I like the orange!