Q related to Omega (new) mainsprings

Nope. Omega packages mainsprings individually - they look like this:



You can buy springs in bulk, in packages of 10, but those are just boxes of individually packaged springs:



They have been packaged this way for 20 years or more. If you look here is the oldest of the "new" style packaging that I have in stock, alongside the previous era packaging:



The spring on the right has a production date of the 27th week of 2005, which is shown as 27.05 on the package. Previously production dates were not included on the package, like the old style beside it - here is the other side:



You will typically see 3 manufacturers for Omega springs, stamped on the shipping rings:



Schwab-Feller, Generale Ressorts, and Nivarox-FAR. Some older springs may not be marked.

Well, that's really old packaging. Those springs are old enough I would remove it from the shipping ring, and make sure it has the correct "S" shape to it.

I don't think there is a universal answer to that. You can always find a mainspring of the same dimensions from a variety of manufacturers, but that doesn't always mean that the spring itself will be the same material, and have the same properties.

So for example, there are different mainsprings used sometimes when the movement is a chronometer grade, compared to when it is not chronometer grade. For example the ETA 2824-2 uses a Nivaflex NO mainspring in the standard and elabore grades, but for the top and COSC grades, it's a Nivaflex NM, which is a different alloy. The dimensions do not change, but the composition does.

So if you order a generic spring for a 2824-2, what alloy are you getting? Is it even either of these? These alloys are proprietary to Nivarox-FAR, so if the springs are not made by that company, you are not getting the same thing.

One could argue it doesn't make a difference, and if that is true or not may be very specific to each situation. But generally people who say the kinds of things you have quoted, are not able to buy parts from Omega, so want to minimize the impact of using generic parts.