The pick Murder vs. Nova is in fact very close and I can see Murder being correct; definitely don't fault you for picking it.
Your P3P3 is definitely interesting. At this point I think the pick is between Aviation Pioneer and Submerged Boneyard.
Diregraf Ghoul is a filler earlygame creature and a much worse topdeck in a control deck than, say,
Walking Corpse due to entering tapped.
I'd basically only run Manalith if I am splashing or have multiple 6-and-7-drops that I want to hit. In your deck, I'm not even sure if a Manalith would be better than an 18th land to be honest.
I think Hired Blade is a worse 3-drop than Aviation Pioneer in general (Pioneer holds back 2 creatures against R/W and provides evasion) and while your deck has some instant-speed interaction, it's not insanely loaded with it, which is why I'd want Pioneer over Hired Blade.
Finally, I think your deck needs a high quality 3-drop more than another removal spell (you're fairly good in this department), which leads me to rule out Dwindle (Dwindle vs. Hired Blade would be closer).
Submerged Boneyard is Pioneer's main competitor. I like having 1-2 dual lands in my 2-colour decks for fixing and like to pick them if I'm good on playables. You have at least 19 playables right now (cards currently in your deck minus Sleep (not the deck for it), one copy of Mind Rot (gets a lot worse in multiples) and maybe Totally Lost (your other removal spells are a lot better, and you're lacking the counterspells to make Totally Lost really effective)), which is a decent number. However, I think Pioneer helps your deck out more than Submerged Boneyard at this point, plus there might be a chance for you to wheel it (the pack overall has a very high density of playables distributed among all colours).
By the way, depending on how the draft goes I'm not even sure what the pick would be between Boneyard and Hired Blade should both wheel (unlikely, but not impossible).
TL;DR : Pioneer is the pick over Boneyard and Dwindle.