One of the players at my Expeditions table is a necromancer wizard, and a member of the Cloaks. Anyone have some general guidelines (with citations, preferably) about how the Cloaks, City Watch/Soldiery, and the nobility regard the undead? This particular wizard has the noble background, and will be Cloak Rank 5 by the time he reaches level 5 and can cast Animate Dead.
My plan at present, should he be seen with the undead while inside the city, is for citizens to alert the City Watch. The City Watch will let him off the hook once he flashes his Cloak's badge of office, but will report him to Cloak superiors for disturbing the peace. They'll express in the strongest possible terms why he should use discretion with the spell.
While I'm confident the player will have his character use discretion, I would like to invite advice on how to deal with it, should the character repeatedly ignore his superiors' counsel.
Nevur: I actually think of a lot of the cities in Faerun that Mulmaster would actually be one of the more Tolerant of Undead (and one reason being its the center of the Banite faith). In previous editions Bane had his own version of undead called Banedead (who were essentially souped up Undead). Having said that, the average person would still fear zombies/skeletons and stuff
Personally I think the biggest issues would actually be with fellow party members: ie if you are adventuring with anyone who is hostile to undead. You run into the whole inner party conflict /table destabilisation them then. Of course its much easier to play to the table (or play with the group you know who wont care). If you are a Cloak and you are of sufficient rank to cast an animation spell and not get in trouble for doing so, then I would have no issue for it. Id of course give my Skeletons perhaps some cloaks and clothing 
Now if he was a Red Wizard AND a Necromancer Id have no issues at all with him using undead, as they rely on them a lot.
I talked about the party member angle with the player already. We have a pretty regular group, and everyone's cool with it. In the event of a drop-in whose character disapproves, the necromancer's player has consented not to use Animate Dead in the interest of avoiding PVP (which is expressly forbidden at my table).
I agree with your assertion Mulmaster is probably more tolerant of undead than many other cities, but I still wonder how far that tolerance goes. I'm led to believe it's still considered distasteful at the very best, but more likely outright repulsive. None of the modules describe the nobility using them, none of the Cloak NPCs seem to use necromancy (not positive on this), and there's no mention of undead in or around the Thay embassy. In fact, I found in DDEX2-5 this telling phrase regarding Azok Throm, "His neighbords have never observed him doing anything wrong, but they are deeply suscpicious of the Thayan man because he's 'no doubt one of those filthy necromancers.'
Then again, module writers have made conflicting statements about adventuring zones before.
What will be more interesting is a return to Phlan. We'll actually be hitting up the S1T2 modules once they hit 5th level, and aiming for level 10 in S2/3. Near as I can tell, Kelemvor is the closest thing to religion Phlanites have, and undead are serious no-no's among that clergy.
errrmm... sorry to say that .. the Dragons first target? He took out the Temple to Kelemvor. So its not at all likely that The Temple to Kelemvor will still be there if we go back.
Kelemvor's Priests and Kelemvor himself dislike dead. Frankly it really comes down to the fact his predecessor (who is back!) love them and most of his high ranking priests were intelligent undead etc. Kelemvor had some Priests whose specific job was to go around ganking Myrkuls created undead.
Tolerant of undead dosnt mean trusted. The average citizen will freak out if they see a Ghoul/Wight/Zombie etc. Any undead that can spread their contagion (and make others of their kind) would be quickly destroyed. A Skeleton Porter? I think it was certainly be disturbing but I I think for A Cloak might be not only awesome but true to station. They do consider themselves above the common folk and its a way of them saying 'look at me and my power!'
Ah, haven't studied up on the S1T2 modules yet, just skimmed them a long time ago. I seemed to recall (and just confirmed) that Cassyt makes a reappearance at the end of Tyranny. Would be awkward if the necromancer was still toting around his minions.
'I found this body in the ruined Temple of Kelemvor. He had nothing to do so he carried my bags whilst we legged it to Mulmaster. Lucky I didnt animate him as a Zombie or it would of been a slow voyage!'
'Thats the former High Doomguide!'