I just changed mine at 43k (have only owned it since 37k) and took a hacksaw to the old one. I was curious to see the condition and found that it was quite free of debris. I don't know if it was original or not...I'm guessing it was. How often to change it? I think the major source of fuel debris is caused by either corrosion from the tank (which will occer if you get water in your gas...water being heavier than gasoline, will sink to the bottom and begin the corrosion process) or stuff you get from the fillup. Which leads me to something I heard...Never fill up your tank when the tanker is transferring gasoline to the station's tanks...the crap on the bottom of their tank is being stirred up. makes sense to me. As in case number 1 above, the best fight against this might be an occassional can of dry gas which causes any water in the vehicle's tank to be absorbed into the gasoline.
How often to change it? Don't know.