When object instances are picked by event, how to pick same instances in the script. For example, I have an event "Player has LOS to Enemy", inside it a JS function "MarkEnemies()" is called, will it automatically pick the same enemy instances as the parent event?
Scripting has no concept of picking. That whole concept is unique to Construct's event system. However you can access the picked instances from script using the IObjectClass methods, e.g. the
Different ways to pass information from the script back to events - set global/local variables, call C3 functions etc.
That's already covered by the Integrating events with script example.
How to use object's triggers, conditions and run actions from the script? For example, if I need to change Bullet angle, I should call something like Player.Bullet.SetAngleOfMotion(n) - what is the correct syntax and where can I find this action/method name?
All available calls are documented in the scripting reference section of the manual. However behavior calls aren't yet supported - it's on the todo list.