If the belt is cracked, replace it right away for sure.
The power steering hose should not be too difficult to change, just a bit messy.
And the valve cover gasket should not be too difficult either, especially if you look up some of the on-line tutorials. But as posted above, confirm the source of the oil leak on your own before fixing these. Clean the engine well, then drive the car a bit and look, (and feel).
If it were my X, I'd stay away from Autozone in terms of parts. You're much better off with someplace like ECS for mostly OEM and some original parts, and someplace like Faulkner BMW for mail order original BMW parts.
OEM / Performance Parts for Audi, BMW, Mercedes Benz, Mini, Porsche & Volkswagen - ECS Tuning
BMWPartsSource.com
If you go to a local dealer for parts, many give a discount for BMW CCA membership.