I wouldn't do a decotion mash out, but then again, I batch sparge.
I haven't made an APA with exclusive Vienna, but I do love a base of 2-row, and about 1lb of Vienna and a 1lb of Munich.
Maybe 6 lbs 2-row, 1 lb Vienna, lb Munich?
Crystal amounts look good, although you could get by with 8-12 oz. of 60L. I usually only mix crystals if I'm doing an amber or brown.
The hop schedule looks great!