The first three images are of Scaup that were photographed on South Padre Island. I can't tell if they are greater or lesser.
The fourth image is of a hen that is hanging out with Redheads. She doesn't look like a redhead to me, but more like the hen of a Ring-necked Duck. There were some Ring-necked Ducks in the area.
The last image is of a shorebird that I think must be a Yellowlegs - maybe lesser? It has orange/red legs, but I think that they can have legs like that (per Sibley) and we surely don't have Spotted Redshanks around here.