Re the first USAAF raid on Berlin - I have see references which state that, while the USAAF raid attempted on 4 March 1944 (Mission 247) was largely disrupted by bad weather, one wing did reach Berlin and thirty bombers attacked their primary target eg see the entry for 4 March 1944 at the following site:
http://paul.rutgers.edu/~mcgrew/wwii...ml/Mar.44.html
Obviously the attack on 6 March 1944 was the first time when the US bombers attacked Berlin
en masse - perhaps the question as to which was the 'first' USAAF attack on Berlin is largely semantic.
That said, it may be that the first US attack which landed bombs on Berlin was the 4 March 1944 mission - there may be USAAF experts out there who could throw more light on this.
Cheers
Boomerang