Joining or Starting a new business with a partner

Hi all,
This is my first post. It seems that the people involved here are really helpful. I am with PSW, thinking to get Tier 1 Entrepreneur visa ASAP.
I have the following questions:

A. If I invest (not £200K/ small amount) and join an existing business started Feb, 11 worth more than £200K, can I claim the points?
B. Or if I start a business now with another partner (British) both with our money and bank loan, assuming the business will worth over £200K in few month, in this case, can I claim the points?
C. If yes, for any of above cases, what kind of documents do I need to provide?
D. Do I need to show any other proof for my part of investment?

Thanks in advance