I admit I know nothing about this. Accounts opened for a hedge fund. Does CIP apply and how? Who is the customer and is this high risk?

The customer is who you say in your BSA policy.
What do you say in your policy for other customers in similar fields?
Does your policy say that the entity only is your customer?
Or all signers as well?

If this is your first hedge fund customer, you have to review the risk and make a determination.

How did the customer come to the bank?
Who are they offering their product to?
How established is the company?
Do they need to register with the SEC or other regulatory agency?
Do they have an AML program?

They are a high risk group so you need to list out all the risks and decide how much CIP you will do.