Good grief, these directions would make my grandmother weep.
I'd do the armhole decreases on rows 1,2,3, 5,7,9, and 11. The front decreases are on (or close to) rows 3,9,13,19,25,31,37,43, and 49.
(I'm putting the directions "Dec 1 st at front slope edge only on 2nd and 6 foll 6th rows." after you've gotten to 27sts.)