I would like to know when do you get the commendation pack for completing an N7 Operations weekend -- immediately, or after the operation ends?
Also are the bonuses cumulative?
So far, the Victory and Commendation packs have always been awarded in the week following the N7 operation, usually on Tuesday or Wednesday of next week.
N7 weapons earned from Commendation packs are just like any other weapon in multiplayer - they start at level 1, and must be earned again to advance to the cap of level 10. So yes, the awards are cumulative - if you earn an N7 Hurricane I in one operation, you can then earn an N7 Hurricane II in the next, or you could earn an N7 Eagle I instead. It's just the luck of the draw.