this is what i would play as of innistrad
4 Wasteland
3 Dark Depths
2 Urborg, Tomb of Yawgmoth
1 Strip Mine
11 Swamp
4 Dark Confidant
4 Vampire Hexmage
1 Necropotence
4 Dark Ritual
4 Leyline of the Void
4 Duress
4 Thoughtseize
1 Vampiric Tutor
1 Demonic Tutor
1 Imperial Seal
1 Demonic Consultation
1 Null Rod
1 Diabolic Edict
2 Liliana of the Veil
1 Helm of Obedience
1 Crucible of Worlds
1 Lotus Petal
1 Mox Jet
1 Black Lotus
1 Yawgmoth's Will

SB:
2 Jailer
2 null rod
3 Mental Misstep
2 emissary of despair
2 ghost quarter
1 Pithing Needle
1 diabolic edict
1 snuff out
1 mana crypt

This unpowered version is more affordable, so it's quite interesting :p

-Does rhystic tutor work fine? With so many land destruction, opponent can't always pay 2 to prevent tutoring, but how many times is useless?
Well, it is another way to get the crucible/strip mine and lock the opponent...you can always cast it when the opponent is taped out to avoid the 2 mana counter. I haven't tested this..it is a new addition i made
-It is ok to have 3 urborg and 2 dark depths? Wouldn't be better to play 2 and 3? or even 2 and 2.
For me works well. Don't forget that your wastelands will also produce black mana this way
-7 duress/tgz? aren't they dead in the middle game?
They might be bad for mid game not always though because in vintage there are many ways to draw many cards, but i would love every game to start with one of these at hand...so no for me they are not many
-Is will useful in this deck? It seems that only works fine with rituals in the grave, and only if opponent countered your creatures.
I rarely used it tbh, but it was good enough to blow a ratchet and then play it again. It also brings back the combo
-2 Diabolic Edict is the correct number?  do you side them out against any pairing? do you feel you want more? would malakir would be better?
2 work for me. Also 2 mana better than 3 (all black as well)Never sided them out so far
-playing grim discovery and crucible, wouldn't 3-4 fetchlands be nice? stifle is not really played this days, althought the deck sacrifices lots of lifes and could be a pain, but drawing less lands in the middle game would be great.
yes fetches could be nice, I could think adding 2..no more because of bob
-have you considered unearth? it's a great way to recover confidant, which is key in this deck. If it's not needed, you can always cycle it for a new card...
No I haven't.With 4 of them in the deck I don't think I need to unearth and I can't remember him in graveyard in the games I played in tourneys so far. Possibly a meta option? It is a nice suggestion tho...
-when do you side in Ratchet Bomb?
Against aggro decks for 1 or 2 and also against enchantments.

Then Dark Times is a good choice or Noble Fish.
Both decks can be played without power