If I slot a new level 85 LI , I will get 6 chances to reforge (assuming I don't add the extra 10 levels).

The Level 10, 20, and 30 reforges ADD an extra legacy to the LI. Levels 40, 50, and 60 give me the chance to upgrade a legacy. Is this correct?

Assuming the above is correct, then is it true that the best time to swap a legacy for another one is after the level 30 reforge and before the level 40 reforge. Is this correct?

From the point of view of trying to get scrolls that allow you to exchange a legacy for a different legacy the best level to deconstruct is after the level 30 reforge. Is this correct?

Question: If I'm trying to get scrolls to exchange legacies is there any advantage to using level 76 versus level 85 LIs? [or somewhere in between?}

Sorry for dumb questions. Just trying to piece together what I have read across many posts and threads.