Well so far:
Convoy:
4 missions daily
1 SS chance for 30 coupons
S and below give between 80k-140k coins
30(?) group contributions ( i don't remember)

Plunder:
3 daily chances
beating an SS convoy gives 50 coupons (so you can earn 150 coupons daily if you get lucky and find/beat 3 SS convoys)
S and below give around 120k coins
40 group contributions per win
Can be attacked 3 times after plunder, each loss takes 50k coins from you.