The following sites seem to answer all your questions:

http://www.transitchicago.com/ventra/

https://www.ventrachicago.com

SM

Thanks for this, already been on these sites but I was hoping someone would have had 'hands on ' experience and could explain in layman's terms but I guess not.

Sorry for the late reply, just got back from Italy.

The old fashioned swipe cards are gome. Insyead you have to register a card a bit like an oyster card.

We got ours from a walgreens. I think CVS also sell them. You have to pay a $5 per card set up charge which the girl said we get back when we renew.

You have to then go online and register the card with all sorts of details before you can use it. I used the apartment we were renting as our home address/phone number and you need to give them an email address, password and loads of other stuff. Beware the card can also be used as a pre paid charge card. Unless you want one of these then do not choose this option (however this is the only way you will get you $5 back)! Weirdly although they would accept my wife having a card and myself having a card from the same address they would not accept us both having the same email address and I had to use another email address when I came to register mine. It was a bit of a faff to do all this, luckily our apartment had a free to use PC in the reception area as we do not have smartphones/tablets etc.

However using the card once it was registered was easy and we topped it up for the second week at Walgreens. We still have the cards (back in the old days we would pass the card which normally had a day or so left on to to someone at O'Hare who were going into the city on the 'L'). As far as I know they still have $5 on each.

I have no idea if you can buy one at O'Hare and use it right away as this year a freind picked us up at the airport and we didn't need the pass until next day.
Hope this helps