You don't need a reverse lever to back tack your thread. There is at least three, maybe four ways to do it. Many of the machines I sew on do not have back tack or reverse levers, as a matter of fact the early ones didn't have such a thing.
As far as changing the stitch length there is a round knob on the pillar for that. Works pretty good too.
Perhaps if you dislike the machine so much you should give it to someone who would appreciate it. There is a section here for offering things, since it was given to you maybe you should use it.
Joe