Go to Sheldon Brown's web site and do some reading. There is a wealth of information here from the very basics about bikes to all sorts of technical/mechanical instructions. Read up on bike fit and proper riding position and things like that. Knee pain could be from being in the wrong position if your knee joint is forward or behind the pedal axle when the cranks are parallel to the ground. Could also be that you just have bad knees.
these hybrids are all-rounders, meaning you can outfit and ride them however you choose. The geometry is relaxed, so cruiser bars work just fine. The short top tube means you have a lot of adjustment in your reach by replacing the stem. If you get a quill step adaptor, you can use modern threadless stems and handlebars. I did this on my 790.
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