Q: What happens with the delivery positions from cancelled orders? Is everybody else moved up the line, or are they just lost?
Someone can actually "cut" in line when this happens.
That's one of the dangers of placing very large orders. Yours orders will automatically be spaced out every X number of days (depending on production rate) and you can never
take delivery of any future orders anywhere before the last date of any previous orders (of that fleet group). So any future orders will always be delivered after an existing order even if there are plenty of openings in the queue before that.
So, place a large order, have the queue fill up and then you'll feel pretty good about it. But as the game goes on and people bankrupt an awful lot of holes in the queue can open up that you can never take advantage of. But other people can. I've gotten dozens and dozens of very popular planes this way. While those who place larger orders paid less per plane than I did due to their volume discounts, by ordering one or two at a time as openings in queues show up, I can take delivery of many more planes that I would otherwise have had to wait years for at the true "end" of the line.