Wireless network solution?

[Davetman]

Let me say first that I am a newbie when it comes to home networking. So pardon me if what I am about to ask sounds silly or completely inaccurate or obvious.

Basically, my neighbor has Verizon wireless BroadBandAccess, where you hook the connection device into a USB port and it connects to the national wireless network or whatever and uses the verizon network as an ISP. (His only affordable option, he lives in a rural area.)

Here is his dilemma:

1) He has the connection device on his upstairs computer. Ideally, he wants to be able to have internet access on his office computer downstairs as well without moving the connection device every time. Is there a way to allow (when connected) internet access through a router (or any other method) to both computers simultaneously?

2) If that is not possible (if he can only get internet on the computer that the connection device is hooked to) can he still set up a home network where he can transfer files between both computers using a wireless router, even though there won't be any actual internet connectivity to the router, basically an internal network only I guess?

My doubts sprouted from the fact that, a router assigns each computer an internal IP, wouldn't that conflict with the Verizon internet device trying to assign him an IP for internet access, when he tries to connect?

Thanks in advance for any help.