OS X V10.7 Lion :: Using USB Stick To Reinstall Software

I recently upgraded my OS on my Mac Pro to Lion 10.7, and have now decided that I want to sell the machine. Therefore I want to reinstall the Lion OS, to wipe it and remove old apps. I created my own USB stick which has the Lion OS on it, and hoped I could use this. However, when I booted from the USB stick, used disk Utility to create a clean Hard drive, I discovered that the OS needs to verify with Apple that it is the correct version. 
Is this right? Does that mean if I was away from the internet I could not reinstall the software? If I was, I could  not reinstall the software. How do I do this if I am working away from home, and not able to use a business wifi? The other issue: is that the next step is "Downloading additional componenets. Your computer will restart automatically" My Mac Pro stated it needed 108 hours to do this, then 7 hours, Now I have a cable modem with 10Mbps download, so I don't have a slow network.  So my thoughts are this:  Do I need to internet to  reinstall software, and if not, how do I do this?  Why is it downloading more components? Why so slow? How many reinstalls are we allowed with Lion? If I have to buy more licenses from Apple, how do I do that? Create new ids?

Info:
MacPro 3GHz, Mac OS X (10.6.4), 4Gb Ram 750Gb HD -FCP 6.0.4