This is a very small airport located roughly 15 minutes from downtown Madison. Arriving an hour before departure is probably sufficient. As somebody who has mostly flown into and out of major airports (e.g., DTW, JFK, ATL, NRT), I feel that there is not a lot to do if you have downtime after getting through security. There aren't as many options for shopping and eating than I am used to. It is very clean and comfortable though. Baggage claim waits are like nothing to me.
TSA lines can vary depending on time of day. I have experienced a roughly 20 minute wait one time. It totally depends on many factors though (e.g., time of day, season).