Great to walk in 'shorts' when you want without taking extra clothing. consider hiking skirts or even dresses. additional middle-layer if you're walking in winter: merino wool leggings.
Whether you wear a rain poncho or a rain jacket: you'll need rain pants. The best rain pants are full-zip, so they zip on the sides from top to bottom. Then it's easy-on over hiking footwear, and easy off. These are waterproof and breathable too.
Public bathrooms are not frequent on the Camino de Santiago. But, cafes, restaurants and bars are frequent, you may find one or two during the day, and these all have bathrooms that customers can use.
Most albergues do not supply sheets and towels, so plan to bring a lightweight one-season sleeping bag and pack towel. If you really want to save weight, consider carrying just a sleeping bag liner if you are walking in summer.
We would recommend that you do not pack a pillow for the Camino de Santiago. We don't think you will need a pillow, unless you're planning to wild camp of course. All albergues and guest houses will have pillows.
It is advisable to carry some cash with you when you walk the Camino de Santiago. The main reasons you will need some cash are to pay for accommodation and to pay your bill in some cafes. On the Camino de Santiago, some albergues will accept card, but this tends to be the private ones that are bookable via Booking.com.
The Camino is pretty much a cash economy, and it's a good strategy to have an average of €200 in your pocket, replenishing at ATMs along the way in cities, towns, and some large villages.
Yes, the water is drinkable all along the Camino, and with sections receiving runoff from the mountains above, it's also delicious spring water. In many towns and villages, they will have public fountains usually in the main square where walkers can fill their packs or bottles.
Daily distances on the Camino de Santiago are between 20 km and 25 km. The average walking speed of an adult is 5 km/3 mi per hour. If you walk at that pace it'll take you 4 to 5 hours of walking per day.
The best approach, especially at the beginning, is to get out and start walking (or cycling if you plan to cycle the Camino). If you are walking the Camino, you're going to want to build up to being able to walk 20km a day comfortably.
People of all ages walk the Camino de Santiago! The average age of walkers is probably closer to 60 than it is to 20! If you are in good overall health and able to walk on uneven surfaces, you will most likely be able to walk the Camino, or at least certain sections.