Subject: K-shell emission and x-rays

I was reading about the process of k-shell emission which generates x-rays.  
Let me recap it to make sure I'm not confused about it:  You shoot electrons at 
a metal target; those electrons hit electrons that are in low energy levels in 
the atoms of the metal; electrons in those atoms that are at higher energy 
levels fall down to fill the space; and when they fall they emit x-rays that 
are of equal energy to the difference between their original level and the 
level they fell into.

Is that correct?  Or do I have that mixed up?  

If that's all correct, I'm confused about why the electrons fall the way they 
do.  It seems like if an electron was knocked out of a low energy orbital, then 
the next highest electron would fall down and emit a low energy photon and 
create a space; then the next higher energy electron would fall, and emit a low 
energy photon; then the next one would fall; and then there would just be a 
cascade of low energy transitions.

Why is there one (or a few) really large jumps down in energy instead of a 
whole lot of little ones?

Also, does a free electron from the environment then become trapped by the atom 
to replace the one that was originally knocked out so that the final electron 
count is the same as it was to begin with?

Thanks.

Re: K-shell emission and x-rays