I never mentioned the hamstring stuff, leg curls or stiff leg deads, a few sets at 8-10 reps would cover them.
As for the 5x5, it really works best if you stick with the same exercise (and there really arent that many good compound ones to choose from anyway), and concentrate on adding small amounts of weight. For example, say you start off by squatting 5x5 on 135lbs. If you get all you reps, next week add a small amount like 5lbs, and do 5x5 on 140lbs. Keep adding in small increments like that, it doesnt seem like much, but if you did that for 8 weeks you'd have added 40lbs to the bar and your body WILL grow to adapt to that. But be sure to also do the assistance sets on another exercise, like leg press, for 8-10 reps. The combination of hitting fast and slow twitch fibres in the same workout is where the magic lies