OK, I don't know the origin of the Lionel Prewar Celebration items, but it's safe to say they were made in Asia, as is everything else these days. So that's not an issue. They were made by Lionel prior to the LCT agreement, and so are probably the most Lionel modern tinplate you can buy. I don't think there's any affiliation with MTH concerning those products.
All I can say is that you had to wait a good six months for those early order items. I think I waited about 9 months for my PWC Red Comet.
As for the rest of the stuff, and the waiting and waiting, and waiting? Well, if the wait is a bother, then I'd not preorder. It's a consistent problem and to think things will be different is a little bit naive.
Remember, the definition of insanity is doing the same thing over and over again, expecting a different outcome. It doesn't change...
If you want a #6, you can buy a real one from the early 1900's for about $1,000 or less. It will be Lionel, it will be American made, and it will be in your hands as soon as you pay for it, excluding any shipping time, of course. It will have a lot more character than the new one. An original #6 and some olive 18, 19, 190 cars makes for a great looking set.
An original #7 is a bit more difficult to find, but there are many older repro's out there that are more true to the original, and they go cheap as well.
I keep telling you guys that originals are the cheapest they've been in 5-7 years. Now's the time to capitalize.