There's no way to do 1 hit kills in MW. I've been playing the game since it was released, there are many places in the game where 1 hit kill wouldn't work.
MW is a server sided game that runs on clocks. Everything is timed, so 1 hit kill onna boss that usually takes 9 hours would get you banned INSTANTLY. infinite jewels? Player history shows if you buy jewels or not.. there are a set number of jewels you can earn , let's say you're top 10% in arena -20 jewels. Top 10 in world boss -20 jewels and that's all you did without purchasing? You'd get shadow banned and investigated if your jewels jumped to 50. Having a VIP level increases the quantity of diamonds you get from login and purchases.
Gamevil have absolutely terrible customer service. Don't risk your main account on it.
M-Coins - 90 percent similar dynamic as jewels except they're more widely available in game (widely, not frequently) you can only get so many possible M-Coins , depending on event, rank. VIP does not affect quantity.
Honor points - identical to jewels and MCoin dynamic. VIP does not affect at all.
A mod that would work would be something like... Free shopping.