Originally Posted by Urbanis

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.

The freehub design provides better support for the axle, whereas the freewheel design has a tendency to produce bent axles. You will also have more choice in configurations and brands using freehub over freewheel.

That aside, if you are not concerned about your weight or riding style damaging the axle, and are pleased with an 11-28t ratio, the freewheel is going to be a cheap and easy solution for higher gearing.

I do wish to note that I personally find it exceptionally easy to bend cheaper freewheel axles, sometimes simply going off curbs will do it.

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

The Nova appears to have a braze on for a front derailer. In that case, you would want a derailer like the Shimano R443 for the front - this one in particular uses mountain cable travel, making it easy to pair with a normal shifter as opposed to needing a more expensive flat bar road shifter.

A new chain would be needed if you're going bigger on the rings, unless the Nova came with extra links and your chain is still in good shape.

Of course, you need the rest of the parts too, such as the new cables and crankset with the triple. There is a good possibility you will need a bottom bracket with a different spindle length to accomodate a proper chainline on the new crankset.

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

I personally really like the Marathon Supreme, and use it on my Pocket Llama. Having also used the Racer, Big Apple, and regular Marathon, I also like all of them too. Each one has a quality that stands out above the others, knowing what you value most would help. I see that you are looking for commuting + touring. In this case, the only tire I would suggest against would be the racer, it has the durability for commuting, easily, but may be a little vulnerable compared to the others when loaded down and taken long distances.

Thanks for everyone's input so far.