SOI and accompanying letter content
Actually your SOI should be no surprise if you know what your Assignment AO rec. was. The board normally is just approving what folks recommend. It spells out the details: What the position is, time commitment, base. It will also give any limfacs if there are.
cficpilot is right. The SOI is nothing more than boilerplate, a blank form. The accompanying letter will give you an umbrella unit, duty location, and if training is applicable in your case, but nothing more. You must have an ongoing conversation with AFPC to nail down RNLT dates, school dates, and an activation date. The actual EAD orders will reflect the reality: the specific unit, correct installation (in my case), and actual tour length.