I'm French, can you help me to find the best mobile plan ?

Hello all :)

I'm coming tomorrow to the USA, more precisely in Chicago to study a semester.

I started to seek information about US operator, frequency you use (my phone will work in usa) etc. I looked on your mobile plan and sorry but they are so complicated lol.

There is something I don't understand. When someone call me, I'm also paying if I understood well ? It's so strange.You prices are also quiet more expensive than in France.

In France since 2012 and the arrival of the 4th operator named "Free" (NYT wrote a huge article about them) we got a unlimited voice, sms/mms and 3Go data plan for 20€ which means approximately 15$

In USA I saw prices about 40 up to 100$ !

Something pretty strange for me also, I saw you've got local operators ! And also that with some local operators when you travel throught USA you are on roaming and so you pay outside the rate plan :s

As you see I've got some questions and It would be great if you can helps me to find the best deal mobile plan.

By the way, once I get Chicago, how can I get easily and quickly an simcard on pay as you go plan. If i go to operator shop in downtown can i Buy one with some top up ? (I'm not sure if we uses this words?)

Thanks in advance to you :)