alpha-Fluoroamphetamine?

[R57]

I know I'm not the first to talk about alpha-Fluoroamphetamine (Rhodium, post 259909) but this looks quite simple:
1. Reduce phenylalanine (in anhydrous ether) to phenylalaninol using Lithium Aluminum Hydride.
2.Fluorinate phenylalaninol with diethyl ammonium sulfur trifluoride (DAST) to give alpha-Fluoroamphetamine.
Two questions though: (forgive my ignorance)
a)With DAST being trifluoride, does this mean it will give up 3 moles of fluoride ions for 1 mol DAST (it's very expensive so this is quite important) i.e. will 1 mol DAST fluorinate 3 moles phenylalaninol?
b)Would recrystallisation/purification be necesasary between the first and second step, or could the DAST be added straight to the reaction mixture?
I assume this will give the free base, so I can make the salt quite simply. Any info will bee very much appreciated!