Having seen your new pictures, it seems you actually have a large one-piece flo-jet, not a small one-piece flo-jet. The adjustable device that holds the float-bowl on is actually your main mixture adjustment - see pictures.
Try not to change the adjustment of the bits in your first picture (i.e. rotate the brass screw in relation to the hex nut). We'll get to that when you are ready to tune the engine.
I don't recommend an in-line fuel filter because they add more stuff that can cause you trouble. The best solution is to keep dirt out of the fuel tank. If you want to add a filter (Ryco make a range of them IIRC) make sure it is not exposed to heat (which would cause vapour lock), is big enough for your engine size, is properly supported, and cannot cause a fire hazard. See why I suggest you refrain from fitting one?
