Well, perhaps if by "mine for a while", you mean "51% the coin while excluding anyone's transactions from the mined blocks", then that would be pretty close to what happened (if I remember correctly).
Totally not.
With a 51% attack you can at most make half the blocks empty, not "exclude anyone's toes from mined blocks".
What he did was perform a 10000% attack, had the difficulty adjust, and then left. What that does, and why that's hardly possible with Bitcoin is left as an exercise for the reader.
Can you explain that please i don't really get the concept.
You send the headers first, and the actual contents of the block later.