...will need to be answered somewhere else.
But answers to a six year old's questions, questions about doors and trains, etc, asked of THE WORLDS BEST MECHANICAL ENGINEER, through the generous spirit of Suttonhoo over at Detritus, those answers can be found here.
Honestly, I just couldn't take anymore door questions, so I passed them along, and THE WORLDS BEST MECHANICAL ENGINEER answered them brilliantly.
Thank you, WBME! Thank you!