As a former Ranger I must say that you are in for the time of your life. I did not realize how much I miss being a Ranger.
I'll be back shortly.
As far as the green beret are concerned you must wait till you are a E-4 or higher to go to SFAS.
I never when into SF. I would rather shoot someone in the face than train a some third world country to fight.
Remember:
Hard times don't last; Hard men do!!
Be motivated and listen to everyone, fellow rangers and the tabbed rangers when you get to the Batt.
Your first few days are going to be rough because they continue to smoke the shit out of you to see if you quit.
Never quit. It will end.
Then when you establish yourself, go to Ranger school, get your tab, and return the favor to the cherries and teach them.
hope this helps.