Firstly with respect to the deadlift:
Deadlifting (especially when from the beginning) is a bit inferior to clean pulls, mainly since it enforces a deadlifter's pull, ass a bit higher, bar slowing down when it reaches your waist and so on. The back position is different (at least when you're a beginner it'll be different) and it'll generally makes you try use that pulling style in a clean, which is a bad thing. After your technique is set in, and also when you're more aware of your back angle and other things in the pull you might do some deadlifts (although still many clean pull for the speed aspect). I found deadlifts were fantastic for me (after lifting for a few years) and really helped me in my starting position, my squatting (go figure) and general weight & strength building. Note that even when a weightlifter does deadlifts, they still use a double overhand grip (with straps), shoulders further back than a powerlifter, and a clean back angle.
As for back squats, yeah they're good but at the end of the day you're training for a big clean, which means getting into the full clean position -> front squats. Again a powerlifter's backsquat is different to an olympic lifter's backsquat (bar higher, back more vertical, deeper) which effects the exercise significantly. Many lifters have excessive backsquats (well over their clean weights) and focus much more on the front squat since it has more carryover, but both are very useful. You'll also find that the gap between a best front and back for a weightlifter is much smaller than for a powerlifter for the above reasons.
