Hi, I am a current student on the APP at EFT, to try and answer your questions -
From my understanding you are not guaranteed the instructor job, you have to meet a certain standard and fit in with the rest of the EFT team, this standard isn't set unreasonably high and you should reach it fairly easily as the instructors are very good.
Uniform you supply yourself (though it isn't expensive to buy in the states and they do supply the stripes), books you can either buy yourself or borrow from the school (they hold a deposit for each item, refunded upon the items return).
You actually gain the JAA (European) licences first even though you are in the US, towards the end of the APP before you start instructing you undergo the FAA conversions.
If you have any more questions just ask or pm me!
