The warning states the issue is coming from custom code as in core WP no function as add_role_caps_to_job_agent exists. Try searching for add_role_caps_to_job_agent in wp-content, to see how this function is getting called and fix or uncomment the call.
The other two notices will disappear once the first notice is solved as WP is trying to set/send headers which is possible only, if nothing was printed to the screen before.