Here, I've made a helpful diagram on the placement of your path nodes.
As for your interior crashing MBP... yeah, editing an interior with a moving platform in it doesn't really work at all in Constructor. You'll probably have to copy every non-MP brush to a new map file and then re-make the MP. Delete any MustChange simgroups in your .mis file, too, before clicking Create Subs again. Always backup your map file before adding moving platforms.