I assume the school will organise the ESTA so her visa will be sorted out.
On the plane she will need to fill in a landing card (possibly the school will do this as well, not completely sure).
You mainly just do passport control on the way in, I think we only did security because we were connecting to an internal flight. So be prepared to queue - at Seattle there was a fairly complicated system depending on whether you had ESTA and if it was your first time using it, again the school should see them into the right queue.
I was asked by customs where we were going and what tour company we were using. He then stamped my passport on completely the wrong page, which I'm annoyed about but hey ho.
On the way back out (in Anchorage) we went through security, which involves the usual - no water in water bottles, your liquids in a plastic bag as in Europe. Take off shoes (not like Europe), take out laptops or 'iPads' (which I took to mean large tablets, no-one wanted to see our 8" tablets of the non-Apple variety) and then some rather complicated rules about what does and doesn't go into a tray before it goes through the x-ray machine. Shoes don't, bags don't, I think only coats are meant to go in the tray but she will have plenty of time in the queue to study the many notices explaining what to do.
Then she will probably have to go through a body scan machine - a bit like a shower cubicle and you hold your hands over your head in the pose shown. I think everyone over the age of 12 has to do this, unless you're travelling with someone under 12. In one direction I didn't have to do it, in the other I did.
Connecting flights are a bit of a pain in the arse, but I assume she is flying direct to LAX?