The main issues are two fold: one, do you have to have the disc in the drive?
The second is if the Steamworks DRM is going to force you to log in every time you want to play the game,
No matter where you purchase the game from, Steam will not require the Disk to be in the drive after the game is installed and activated.
Steam will not require a Log In if you run the game in Off Line Mode
Now, there will be no other discussions of Steam in this thread as we already have several Steam Threads. If you have any more Steam Related questions, then use the linked thread for those. Any other Steam Posts in this thread will be deleted.
http://www.gamesas.com/index.php?/topic/1119705-can-someone-explain-the-whole-steam-situation-to-me/
Please continue the Pre-Order Bonus Pack Discussion in this thread.