The best thing to wash them with is eco-balls, as you can get a powder build up if you use too much powder, making them less absorbent and also can make them smelly. That can't happen with ecoballs. Wash regularly on a long 40ºC wash, and perhaps once a fortnight on 60º, although if your baby is ill, always use 60º. For stain removal, add a tablespoonfull of Ecover laundry bleach to your load.
Hang outside, even if the weathers not good, as the sunlight/ daylight will remove any residual stains, and sunshine is a natural bacteria killer as well! In the winter, they won't dry outside, but a good blow in the fresh air is really good for them, so hang them out for a day, and then bring them in and pop them on an airer in a warm place to finish off.