Findo, if you clear me via SAM climbing to FL160 and subsequently tell me to cross SAM at FL100, I will take FL100 as my climb limit until I am recleared otherwise. If you tell me to cross SAM 'at or above FL130', having previously cleared me to FL160, I will assume that FL160 is still my climb limit. In your other scenarios, if you change a lateral clearance by re-routing me then I will obey any earlier altitude clearance unless you tell me otherwise.
In the descent clearances scenario, I will always assume that a 'decend FLXXX by...' clearance stands through controller changes unless I am told otherwise. Equally, if, after a controller change, I decide I can't make the restriction imposed by the earlier controller, I will tell the current ATCO of the problem. Sometimes circumstantial evidence (TCAS, other clearances) will suggest that the restriction may no longer be necessary, but I'll still check!