I keep saying this, people are giving the Sandman thing more weight than it really has... According to the plot description and leaked pictures, the burglar from Spidey 1 worked for Flint, he killed Ben to hijack the car, so if Pete hadn´t stopped him, Flint would have bailed out. Peter´s responsibility hasn´t changed. Second, from some signs the movie been showing - Peter telling Harry he didn´t kill his father - I wouldn´t be sure it isn´t a red herring...
As for the costume, it´s these things where you can´t win with the fanboys... If GG had a 100% accurate comic book look, let´s face it, he´d have looked ridiculous on screen... But then people went crazy over the "Power Ranger" costume... Now Harry has a costume that looks much sleeker, now it sucks cuz it doesn´t have the "Power Ranger" mask... That´s why the Batman & Robin kinda thing gets made, if you try to please all fanboys you´ll go insane...