Personally, I wouldn't try a kidney cleanse while still doing a colon cleanse. I would stop taking the P&B shakes at least a full day before doing either a Liver Flush or a kidney cleanse, or even finish a Colon Cleanse before moving on to clear out the kidneys, etc.
My reasoning? P&B shakes are 'knocking loose' old toxic buildup on the colon walls and pushing them through the colon. In the process, some toxins are released and need to be handled by your body, which is very hard work. Kidney cleansing and Liver Flushing also release toxins to be flushed away. If you try to do all of them at the same time, or back to back, you're not giving your body time to handle the released toxins before dumping more into your system. I'd pace myself and address one issue at a time to allow my body time to heal and recover between rounds.
Listen to your body, help it heal itself, don't overload it even more by pushing too hard too fast.
As far as the apple juice, 100% organic fresh pressed is best, but if all you can get is plain old juice with no preservatives or additives of any kind, that's ok. A good rule of thumb for anything you eat or drink is the fresher and purer, the better. Not everyone lives near an organic farm or orchard, though, so sometimes we just have to make do with the best we can find. Do try to avoid "from concentrate" if you can, but again, we have to do the best with what we can find.