Also, if industries with neutral docks / helipads exist, is it possible then to make industries with an integrated neutral bus stop / loading bay ?
No, it is not possible for trunk/stable version.
My experimental openTTD server: 220.127.116.11:3979 non-standard client, now testing: JGRPP http://tiny.pl/ggnch
Projects: Reproducible Map Generation patch
, NewGRFs: Manpower industries, PolTrams, Polroad, 600mm narrow gauge, preindustrial houses, wired, ECS industry extension.