Chicago has really great public transportation, if you're into that! Information about fares and transportation maps/schedules can be found here: http://www.transitchicago.com/ Otherwise, taxis, Uber, and Lyft are all great options for getting around the city.
There is a pay to park lot directly next door to the venue- $12 for 8 hours. Also, the large stretch in the middle of the block is free and unmetered. In general, parking near the venue can be pretty limited, so rideshares are a great option for getting to the venue stress-free. If you're taking the train, the venue is near the North/Clybourn Red Line stop or the Armitage Purple/Brown Line stop.
Normal wedding attire. But if dressing up isn't your thing, wear whatever floats your boat!
Yes.