Menstrual cups

Erin
I need some advice/knowledge about mensrual cups. I want to be kinder to the environment and to my body and am thinking of getting one. I use organic cotton pads and tampons because I am allergic to cheap products, but it is so expensive! 
I have a few questions about menstrual cups first though:
1. How messy is it? Do they leak?
2. How easy are they to put in?
3. Do they hurt?
4. Should you have more than one?
5. How often should you empty them? 
6. Can you wear them
To bed?
Any extra pointers you may have would be greatly appreciated
Thanks ladies!! Xx