First, Ranger and Explorer front end parts are interchangeable, so that is not the issue.
Second, you have just installed new springs that are not broken in. Drive them around for a bit and see if they settle in.
Third, the pocket for the spring pig tail is on both sides. Twist the springs until they settle into that pocket. Until you do, you'll see that bowing.
Fourth, unless you do something with the front anti-sway bar and shocks, the new springs won't really do you much good. The shocks and bar are limiting the suspension movement. There are ways to address this issue and you can find a post here:
http://www.explorerforum.com/forums/showthread.php?t=237302
Fifth, you can get by without drop brackets, but you will have to adjust your front end alignment, possibly using higher degree bushings for your upper ball joints to get camber back into place.
Sixth, your axle cannot "push forward" unless your radius arm bushings are worn out. With an older truck, that is entirely possible, and you will have to make a decision as to replacing those bushings. Along those lines, if you want increased travel for off-road use, don't use poly bushings, as the really hinder the amount of overall travel you can get. Even adding new rubber bushings can hurt wheel travel some, but worn out parts don't locate the axle well and can cause drivability issues.
Finally, the springs you bought are in all likeliness too stiff, but you'll have to find that out by driving the truck.
