Auto 45-65 is the best one. What that does is it basically does a prewash and then it passes the water through a sensor that looks at how dirty it is. If it's not very dirty it will do a cooler, shorter wash at 45 degrees which uses less energy and water, but if it's dirty water then it will choose a higher temperature for better cleaning. I like that because it seems to make the best choice between energy and effectiveness.
The top rack will run cooler and with less force than the bottom rack, so put anything plastic or delicate on the top rack, and anything that's more robust or needs a more heavy duty cleaning on the bottom rack.
If you ever need to do something at a higher temperature there will be a hygeine/intense setting. You can also use that as a cleaning cycle. Those are the only two settings I ever use.
Dishwashers dry by putting really hot water on everything as a final blast. that heats up items like glass, metal, whatever plates are made from etc and the heat will cause the water to evaporate so they dry, but plastic doesn't heat up so plastic items will always have water drops on them and wood will be damp (and eventually warp and crack). So beware of this when emptying or you will curse it as it drips water down your sleeve/in the perfect place for your sock. Also anything that has a depression in the top will collect water.
If you can get hold of a manual for the dishwasher, it will probably explain the wash settings in more detail.
If you get fine sand on everything after washing you need to clean the filter and maybe top up rinse aid. All in one tablets are a con - you need rinse aid and salt even if you use them. You can therefore use the cheapest single tablets (or we find liquid gives a better result).