In a lot of spin classes, an instructor will have you getting up and going back all throughout. Often while standing they will have you increase the resistance to simulate a hill, then have you return back to your seated position at the original resistance.
As for the muscle groups, it does work similar group as running, through not completely the same.
And as for wear and tear on the pedal you have nothing to work about. I work maintenance at a fitness club, with 4 spin classes a day, and 6 on weekends. Over the last year and a half, I've only had to change pedals on 2 bikes, so it is safe to say you have nothign to worry about