Does API v2 auto return the droplet IP and password when it is created so you can send the login details to your clients?
No, it's not possible to get a droplet's root password via the API. I would recommend adding your client's SSH key and then selecting it when creating the droplet.
Does API v2 allow a method to view server stats (disk, memory or bw) so my clients would be able to view these details?
That is not supported at the moment as gathering system stats such as disk/memory/cpu usage requires access to the droplet itself which is impossible without an agent running on the droplet. See Add Ram & Disk Usage to Resource graphs. – Customer Feedback for DigitalOcean.
You can view the API documentation here: DigitalOcean API.