1. Stopovers are not an issue in using an eVIP, provided the underlying fare allows them.

2. Madison is west of Chicago - so you have changed direction and are coming 'back' from a point further away from your origin (HNL), so your 'one way' is over.

3. In my experience, it's unclear if the 3 (upgraded) legs have to be consecutive. As others have pointed out, Eagle segments don't count. However, I'm not sure if you were going say HNL-LAX-DFW-JFK-LHR (all mainline) whether you could skip one of the intermediate legs. I assume you can - it's a one way trip and you can upgrade three segments ...

4. As others have pointed out, using segments of a xONE to go Chicago-Madison and back seems a bit of a waste - how much is a separate ticket?