Hi @waykar
When your workers connect to the server, they open a long poll connection requesting for workflow and activity tasks. You can find an small explanation here Workflow vs Activity - #3 by antonio.perez, let me know if it helps.
Will it utilize container 3 worker threads as well?
Temporal server will do a fairly distribution of the load (tasks) across the workers listening to the same taskqueue, so it is highly possible that astivity tasks get dispatched to all workers.
If we have an API being invoked in container 1 which triggers WF1, and on container 2 we have WF2 being triggered.
The same mentioned before for activities applies to workflows. If you have more than one worker listening to the same taskqueue, when you schedule a workflow it can run in any worker
Antonio