I prefer single speed bikes because I like my bikes clean and simple as possible and they fit my current riding style. I rode a cruiser with two speed kick back for years but found I rarely needed the lower gear. Neck injuries ended road biking so single speed cruisin is good for me!
I've never tried to install a Nirve kickstand on a Schwinn but it would need to have the collar to accept the Schwinn retainer pin. Do you have a picture of the kickstand you want to try?