Generally, follow the recomendations of the operators manual, but if there are no specific numbers given, definitely by 100K miles. If you have been purchasing fuel from places that do not move a lot...
should be 2 screws holding it in place. you need special tool (sorry, don't know the actual name) that removes the gas lines from both sides - check you local parts store or flea market. it is a...
I have a 92 Trooper and my fuel filter is located on the frame rail, passenger side of the car near the rear tire. Just clamp off the lines on boh sides of the fuel filter so fuel doesn't go all over...