Hopefully this helps:
To get the time passed for this tick, use
ar dt = this.runtime.getDt(this.inst);
dt is the time, in seconds, that the physics simulation should advance. That should keep the speed steady no matter the framerate.
To get a callback when an instance is destroyed:
I just remembered there's already a function for this, because other parts of the runtime need it. Call
untime.addDestroyCallback(function(inst) { alert(inst.toString()); });
and it will alert the instance ID whenever something is destroyed.
To get a callback when an instance is moved or rotated:
There's nothing for this right now, but for the next build I've added a method for instances:
nstance.add_bbox_changed_callback(function(inst) { alert(inst.toString()); });
This will alert the instance ID whenever its bounding box is changed (x, y, width, height or angle is changed). Try to only add one callback and only for instances that really need it, because otherwise it'll add unnecessary overhead.
Hope that helps, let me know if there's anything else you need!