hey jet lover,
i did my faa written last month, gleim is a pain to study on.
i ordered the books online, and it cost me around 3 mill for the whole atp prep set.
gleim gives you about 1700 questions and it is quite time consuming so if you are looking to get it done asap, i would recommend the atp prep course.
you go there in the morning, do they prep which is questions of 600 and do the exam in the evening.
the validation is only required for when you wanna do your sim check, for written you dont need it.
also you need to get tsa clearence before your sim