How does broadband with cellphones and laptop work how much extrea is it and does us cellular phones shave it?

Broadband on a cell phone network (i.e. on a netbook) work through the cell phone towers.  The speed generally depends on what type of cell phone tower, the carrier, and what the carrier enables.  Thus far 3G is the fastest data transfer speed you can get on a cell phone and Sprint is currently working on the 4G.  Basically what happens is that you either by a USB network aircard or a netbook with that capability already built in and you can surf the web at 3G network speed anywhere there is a cell tower with 3G wireless.  Generally it costs about $60 a month for broadband and you are limited to 5GB of data access per month.  Generally that's about an hour of normal youtube videos or half an hour of HD youtube videos per day.   Thankfully, netbooks and aircards have counters so you can keep track of how much data transfer you've used.  As for a on a cell phone, it usually costs about $10 more a month (on top of what you pay for your voice/texting plan) for unlimited data usage and once again is limited by the speed of the network.  U.S. phones do have these capabilities and practically any contract phone you buy will be ready for internet usage. 

The terminology you are looking for is "Tethering" do a google search for (your phone+tethering+us cellular).  Us cellular does have a data access plan called the "Mobile Internet plan."  Price: $14.95mo

Good luck!