I shoot it twice a week because of the advise ive gotten from guys here whoi trust.
However i know guys who shoot it E5D and even once a week and are happy with results.
I'd imagine that shooting 250mg E5D would put you at more risk of acne that 250mg 2x/week. Due to less stable blood levels. Also you'll get better results from 500mg/week. So i'd recommend 250mg twice a week or E3D.
As for extra care for acne, i'd recommend extra showers and some good bodywash, "clean and clear" or whatever its called!