Questions:
1. Is there a compelling reason why I would change from freewheel to freehub? I don't understand why this difference is important on a practical level. It sounds like Ed Wong's thread-on freewheel would do the trick of improving the gear cluster.

2. What components would I need to add a front derailleur and triple chainring to the Nova?

3. Any suggestions for tire upgrades? I'm considering either the Marathon Racer or Marathon Supreme.

Thanks for everyone's input so far.