The apple juice and/or magnesium malate/malic acid is all I've ever used as preparation. There have been times I've done apple juice more days than necessary because something came up that I couldn't do the flush when I planned.
I have always felt fine after flushing. No recovery time needed. I always stick close to a bathroom the next morning!
I believe the olive oil may help everything to slide out easily - I don't know for sure - I think it causes our body to expel bile helping the stones to come out. I don't believe it clogs the liver in any way. I do know that fresh, extra virgin, organic olive oil is very good for us and most every Liver Flush protocol calls for it.
Please don't be frightned of it - the ingredients are common items not known to cause any problem and there isn't any pain involved when the stones come out.