The AK74U is better almost on all levels in real life. It's an upgrade to the AK47. The bullets are smaller which causes increased accuracy and a weaker recoil. But of course, The M16A4 dominates them both.
If you sent your game in and Gamefly processes it and sends your next game all at one time it will probably take between 3-6 days. Of course it will take a little longer if it takes awhile for your next game to ship. It usually takes Gamefly 7 days total to process my game and for my next game to arrive at my house.