They vary. You can find a table here: http://www.illinoistollway.com/portal/page?_dad=portal&_schema=PORTAL&_pageid=133,1495185
I cant tell you exactly how much but it is more on the expensive side. Luckily there is really only one major freeway that requires a toll. It is the E-470 loop which is obviuosly the loop highway...
it depends on which way you are going.you could only be using NJ turnpike or Garden State parkway so it depends!!
Tolls are $6 going from Philly to DC and $11 the opposite way.
Not yet