Change what you need to make the bike work for yourself.

Don't just do upgrades like a new crankset without a purpose. You may have troubles getting the chainguard just right with a different crankset anyway.

If something is rubbing, then a little judicious bending can help.

One thing you might consider is an internal gear multi-speed rear hub. It would mean rebuilding a wheel if you don't find the right wheel. Many have gearing from about 0.5 to 1.5, to give some "overdrive" for the small wheels, and smaller gearing for hills.