What is the advised configuration to allow for several condor_startd daemons on each execution node (e.g. several pilot jobs per node)?I assume this is done by using some random port between the condor_startd and the collector, but I could not figure out how to do this.
Not sure what you're asking about here. The root HTCondor configuration doesn't change if it's running pilots, and jobs can't use the root HTCondor's shared port daemon. What's the specific problem you're seeing?
For most firewalls, you just have the pilot use its usual collector for CCB and that's all you need to do.