It depends on the car itself and the fuel filter cost. Generally fuel filters for Toyota/Lexus are in the range of 30 to 40 dollars and another 20 dollars should help change it in a mechanic. But could be less also for labor. These are just estimated answers because you fail to provide further info in the question!
You should change your fuel filter every 90,000 to 100,000 miles.
Simply unfasten the existing fuel filter with a pair of pliers. The replacement filter can then be inserted into the gas line. Doing this will help the engine to run much more smoothly.
Yes, but not much. You must be VERY CAREFUL when releasing the nuts so that you don't crack the fuel line! If you do, the line should be replaced the from the filter to the next fitting (NEVER try to splice the gas line!).
About 12-15 dollars. It is an easy replacement, so do it yourself and save more $
Replacement filter cartridges can vary in price depending on the filter that the cartridge is inserted to. In general, a replacement filter costs about 40 dollars.
It depends on how much you drive it. It could also depend on what type of fuel you use. You should change the fuel filter between 30,000 miles clear up to 100,000 miles. or if your car does not start and there is no fuel in the filter, then you can change it then.
It depends on what vehicle. A 2001 lawn mower's fuel filter could only cost $5.00. A fuel filter on a car/truck that is in the tank on the fuel pump may cost $500 + to replace.
Depends on who does it. Call around for estimates.
never found a fuel filter and it has no timing belt
This varies so much from car to car. My car does not even have a replaceable fuel filter. Best advice is to check your owner's manual.
3.5 liters without filter replacement. 3.8 liters with filter replacement.
Your fuel filter should be changed every 50000km. Have it changed at your annual checkup. It doesn't cost much and really increases your fuel economy. (specially on an older car.)