Hi Chris,
Unfortunately, the LiveAPI does not give us access to the Chain Selector. That means that, unless Ableton expands the LiveAPI, there is no way for us to mimic Chain Selector behaviour in Videosync.
You could map a chain’s mute button to a Macro, and use the mapping’s min/max values to enable chains at a specific value. If you set the values to as they are in the image below, ‘Chain 1’ will be enabled when the Macro’s value is 0. ‘Chain 2’ when the value is 1, and so on. Although the Chain Selector is a bit more flexible, this might work for you.
Regarding your second question, I’m not sure what you mean with ‘separate iterations’ and ‘combining effects’ and what your expected result is. Could you elaborate on that a bit?
Best,
Hidde