Chain life

[Yan]

Hi, my wife is considering buying her first bike and GZ250 is an option (particularly because my first bike was a GZ250 and she liked the looks of it very much). There is a few of them available within an hour from us, some with low mileage (couple of thousand miles), and a few with around 10k miles on them. My question is basically this - how long does the chain last on GZ250 (I understand it depends a lot of how and whether it was maintananced, but I am looking for an average number), and how hard it is to replace it yourself? Do you have to cut the old chain and then use that tool (rivet ?) to put the new one together, or there is a way to get an already assembled endless chain on the bike?

Thanks!
Yan