1. They're easier to maintain. I commute everyday.
2. I don't rightly remember. I bought my bike from a recycle-a-bike shop. It's a late 70's bike and I hate those damn friction shifters on the top tube so I decided to try fg. Had a blast converting it and building a new rear wheel.
3. I ride a geared mountain bike as much as I can. I used to ride flatland/a little street. I really like all aspects of cycling.