Originally Posted by
krunksmash
2) this one is a hard question to answer for any spec. personally the way I use it in is as an oh $#%* button a way to get 2 runes when I need them now or as a way to fill in dead time in my rotation, TBH I can't really help you here, it vastly depends on the situation. if you can spare a glyph slot get the glyph of outbreak and you can use it when ever you want and only need to spend 30 RP to get your dots back, and TBH thats my best suggestion, use Glyph of Outbreak and just pop Plague Leech when ever you feel you need it and have the 30 RP to spare.
3) this is an easy one, your top 2 in order are multistrike and mastery, multistrike has X% chance to grand 2 extra attacks for 30% damage, that makes it slightly better then crit and its stat scaling seems to be much nicer then that of crit, additionally it synergies well with your mastery that increases all your shadow damage. after that there is some varied views on whats best but I'd say that haste = crit = versitility, for your 3rd secondary just pick the one that fits your play style best.
EDIT NOTE: forgot to say that Multistrike also takes #1 due to Nacrosis.