Q - after max donate to group, should upgrade gear?
A - yes if can, the game need specific power for you to able to do certain quest/event/pvp

Q - should spent coupon for level 2 magatama, then start saving for event?
A - actually i'm a bit conflicted on this, some will say spend while other say save.
Truth is, spending to get might (for me) like magatama, mood, cloth help a long way;
so i recommend spending it instead.