Corrections of completed quests etc.

Hi Ginger,

right now I've completed all the quests on dashboard with the awareness (due to experience of the many quests done, the new informations acquired from forum, etc.) that  I did a lot of mistakes. Are you always of the opinion  to make no changes on already marked quests  as you told me in a previous post?
Other questions (not really important) about the comparison with other people of the community: in which way is chosen the peer and what is the rule of scores? Which is the rule to define the correct (or the most correct) markings among the 15 of a completed quest?