There is indeed a mailing list! when you move onto the final step it'll ask you (nicely and once).
The quantity bump gets shown as a warning because at some extremes the optimizing algorithm may choose to increase the overall quantity even if it costs you more than at a lower optimization level. Lets say you picked $100 worth of MCUs, and it knows it can get 30% more MCUs for 10% of additional cost - it may go for it. In such cases we thought the user would like to know.
Unfortunately we have no way to calculate the shipping at present... but the generic parts locator is a great suggestion, we'll do it!
The quantity bump gets shown as a warning because at some extremes the optimizing algorithm may choose to increase the overall quantity even if it costs you more than at a lower optimization level. Lets say you picked $100 worth of MCUs, and it knows it can get 30% more MCUs for 10% of additional cost - it may go for it. In such cases we thought the user would like to know.
Unfortunately we have no way to calculate the shipping at present... but the generic parts locator is a great suggestion, we'll do it!