Hi Jungleboy.
About walking in the riverbeds, if you go to Google Earth - Almeria, track north to Huercal de Almeria and you can zoom into the river, you will see that the local farmers use the river bed as an informal roadway to get to their market gardens, so there is usually a "smoother" track to follow.
You may want to look at the route after Santa Fe, the camino heads for the hills, its possible to continue along the river bed and exit to the left at the "Ermitia Virgin del Rio" gain the road A1075 to Alhabia. The camino goes to the left just after the first bar in Alhabia on this stage there is a road beside the riverbed.
There were a few wet areas when I walked this way a couple of years ago, but nothing too bad, you could ask in the bar in Santa Fe about any water issues, don't feel bad about missing a few hills, there's plenty to come!!!
Yes I have walked this way (twice)
Regards
George
Edit... I cannot remember any riverbeds on the Malaga route, plenty of olive trees though!!