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Development of the externally-facing APIs you need is open. The component for pc-based control is at
https://github.com/krontech/chronos-web-interface. It's a HTTP-based API, which is a wrapper around two internal APIs. Those APIs are the
coordinator api written in Python and the
video api written in C. Neither are ready for use yet, so the http api you need doesn't work yet. The coordinator api only exists in mocked form and is (well?) [https://krontech.github.io/chronos-gui-2/D-Bus.html]documented. The video api, which actually works for realsies, is undocumented at the moment so you can't use it either.
We're hoping to have the APIs released by the end of June now. Previously, we were hoping to have them released by the end of last January.
For your second question, it sounds like setting a delay as you describe will do what you want.
Hope that helps!