Kodak can and do make the 100 foot bulk rolls.
It is just that the left over finishing and packaging line/machinery for them is pretty well their oldest and most inefficient and most labour intensive of anything they use - which means high cost/roll, leading to high prices for the consumer. That historical remnant dates back to the days when those film loads were used by high volume users who employed them in ID photo systems and school photography, and who bought the rolls in quantities that resembled the quantities that motion picture productions used. When that market disappeared, most of the manufacturing capacity dedicated to it was scrapped.
For that cost/price reason, colour film hasn't been considered practical for the 100 foot loads, and the expensive black and white 100 foot loads are probably only made infrequently.
It would cost a lot of money to modernize that line - even if only to the vintage that Harman is using - and any such expenditure needs to be extensively justified before such decisions are made. This is the reality of the modern film business, with its tight controls on available capital.
IIRC some labs, Kodak??? used some sort of fancy punch to punch codes in the film ends. I maybe am just imaging this
Yes - Kodachrome and Ektachrome processed by Kodak.
The customer films were all spliced together in one long roll, run through a movie film processing line, and then separated at the end for return to the customer. The holes helped ensure that the right customer got the right film.