See if any of these links point you in the right direction....
Question 1 - The fuel filter, what is the trick with changing that?
2004 4.0 fuel filter change
The year is not the same but they are all similar in a way. The trick is just figuring out the best way to release the clips. I just used a flat head screw driver on mine.
Question 2 - This Ranger is a V6 but I am unsure what a flex fuel is? It has a funny little badge on the tailgate with a leaf if that means anything.
Some good info in here.
Question 3 - When you close the door to drive off the "Door Ajar" light stays on a bit longer than normal along with the interior dome light. Any idea?
door ajar light staying on?
WD40 seems to do the trick for most people with this problem.