As far as the total achievements go, I think it is a true sum of all the instances of each achievement. However, next to each achievement, it only shows the most significant power of two in the binary representation. So, if you have 70 +5 posts, it will only show 2^6 next to that achievement, but will contribute the full 70 points to the total.
I remember reading about the military's cheating a while back. Here's a little background about how the US spent $253 million dollars on Middle East war games in 2002 and fixed it so they would win.
No such luck.
Imagine if free speech were free (well $50 one-time hardware cost)
What happens when there's no more credit left?