My question involves business law in the state of: England

Hello,

Me and a guy are starting up a new online project. We will be doing it 50/50, we need to get some sort of contract set up between us to define responsibilies, ownership etc. There are a couple of things which I don't know and was hoping that someone here could clear it up for me.

1) What should such a contract consist of?
2) The person I am working with is 16, we are both from the UK. Any one know whether he can sign this himself or whether he needs a guardian to sign for him?
3) Anything else we need to be aware of?
4) Anyone have a sample contract that we could tweak to our needs?