I think the "weight" info means that when Niko runs, he will accordingly shift his weight. No more popping a complete turn 500 times in one second with the animations remaining the same as though he were running forwards.
Street names will be helpful too, especially if you need location specifics. No more "turn here, then here, then here". Just "at the corner of Blahblah Rd. and Wtf Ln.", which is cool I think.