2005 3.5 engine rev while shift

Why does the engine rev between gears in my 3.5 altima when I put in the clutch? Also, has anyone else notice significant tourque steer under hard accel. like tourque steer that is disproportionate to the actual torque being put down? Any ECU flash for the 3.5 SE that is fairly cheap yet? Also anyone evr put G35 wheel on an Altima? Would they fit? I got lots of questions....sorry.