My two cents:
-Tach is definitely misaligned (a little bit but it is)
-No idea on the discoloration of the metal but even if it is, who is going to see it?
-The screws should not be blue...
This is an "authentic" TAG Carrera auction on ebay (not mine) and you can see from the pictures of the movement, no blue...
http://cgi.ebay.com/TAG-Heuer-Carrera-Legend-CV2014-Auto-Chronograph-Watch-/200586438716?pt=Wristwatches&hash=item2eb3e2283c#ht_2027wt_905
Regardless, looks like a really nice watch! If you're going to scrutinize over a tiny misalignment in the tach bezel and a couple blue screws where no one can see, maybe a gen is a better road to travel?