The SDK is still a work in progress and hasn't been finalized or made public yet. We are definitely deep into the process of documenting everything and preparing it for the future, but there is no release date yet, so please stay tuned to future announcements/videos.
Yep, the forums are probably the best way to get in touch with us - multiple people from the team read and answer these threads in addition to the community, so you're more likely to get an answer here than email / twitter / etc. Or if you have private client work or other stuff, feel free to DM me here.
Is there an SDK yet? Teaching an animation class and it would be great to add that in. Thanks.
Sorry, it's still not ready yet. Though we use the SDK internally already, before we release it we want to make it easier to use and less likely to change in the future (so your extensions aren't broken by future changes).