event exclusive questions

just a few questions for those in the know...

looking on jauce, i see many of the pieces have numbers. do they relate to the year of release, or what number they were in the release line up? i have seen two different #01's, so does it restart each year?

some have matching engine and tail cars. do they also do middle cars in the case of bullet trains?
https://www.jauce.com/auction/k268247678

would this style of engine have had a matching tail car? i have a middle car that matches.
https://www.jauce.com/auction/q175091680

there will likely be more questions when i think of them. thanks in advance!

[Super]

I always assumed that the large numbers where the year they were given out with admission for that years Plarail Expo. Like in your second link that would have been for 2004. I could be wrong as it is just what I assumed.

thats what i thought, too. then, since i see the same body style with different colors and numbers, whether they restarted each year with a certain body type, or if each type is available each year?