✔ 最佳答案
1) You can find the cheap youth hostel online, and they have rating from the people who have stayed there before, (eg. youthhostelworld.com ). And if you really choose to stay with many people in a room, better to bring a lock for your properties. if you can afford, B&B is quite a good choice.
2) For london, bus is cheaper , but if you are not familiar with there, strongly advice to take the tube, and it always have instruction on famous tourist site.
3) English is the most important as you go to different european countries with different language, cannot say which other is most important . As I know most people in Netherlands speak English rather than dutch, Germany and Switzerland speak germen, France speak french, and Spain speak spanish. So there is no another language other than english you can speak for more than 2 countries you mentioned.
4) other than those necessarities, a bag that is tied around your waist is needed (to out your cash and passport).
5) Normally from May to Oct !