Taxis are pretty cheap in chicago, you can get the one week or tourist pass from a near by drug store, from lake shore dr, i guess you can take 155devon, few blocks after western ave you’ll see a Osco drugs, CTA passes are available over there. Also there is a train station on lake shore and they should have CTA passes in the train station too, red line will take you straight to downtown. Rest get the bus/subway maps and you should be good to go.
Places I recommand:
The Art institute of Chicago
Museum of Science and Industry
Navy Pier
Shedd Aquarium
Sears Tower