I had my misgivings about this one, mainly by the word of others (the main issue being their personal mistrust of the author as a D&D guy, fearing this would be a way to "D&D-ify" HQ, to the detriment of the franchise). To this day I haven't yet played any of the quests, only studied the book and read comments from others. We've playtested the Bard (and I've made my own custom aesthetic revamp of the character in the form of an Orc pirate but he also works like how I imagine a Cleric could work in HQ too).
To me, if we were going to fit this set into the lore of HeroQuest, it would be as a rather late stage adventure... the new war against Zargon has raged on, and things are changing. The toll of time and the stress of the conflict are finally starting to catch up with Mentor, hence his need of "help" is maintaining his vigil both against his former student and his communications with the heroes. Zargon's will has also faced serious challenges... and the war isn't going so well for him either, hence his troops are starting to abandon their posts, and defectors are coming through, many disillusioned with his promises of power and that's how the various "neutral/good guy" Orcs are justified. So I think I disagree more with the suggested official placement in the chronology than the existence of the pack itself. As a kid I certainly loved monsters, and the monsters as the bad guys was the accepted norm but I was also super into the idea of having (a few) good guy type monsters, not necessarily in HeroQuest, but in my imagination, so I wouldn't have completely rebelled against the idea of such a thing had it been presented to me that early. I think when Warcraft II came out I rolled my eyes slightly but quickly accepted the idea that maybe once, not so long ago, the Orcs were a noble people, who fell in with the corruption of their leaders and the dark side of magic at a certain stage. Every fantasy fiction that has "orcs" doesn't necessarily have to copy each other. But I understand that if Warhammer Fantasy was the real thing for you, then you'll want that back of course. I don't think I really got those connections until the 2000s at the earliest, growing up in the US (I think it was '98 when I discovered WH 40K, a hobby which seemed way too expensive for my taste, but still didn't know the explicit links with the lore until around then thanks to sites like this ones immediate ancestor Agin's Inn).
I am also of the opinion, and I don't think this is too controversial, that PoT and SQT (like Rogar's Hall) were not written primarily for people who were brand new to HeroQuest, but was targeted at those who played the game in youth, but were (like Stephen Baker when he wrote the other aforementioned quests) returning to the franchise with nostalgia after three decades. Yes, those same people would most likely be introducing it to their kids as well, so you're anticipating veteran players who might have a newbie in tow. Old familiar things with a few new twists mixed in...
Hence it's been a long time for the Heroes, and for the players who controlled them... thus it may not seem so jarring or repetative that they are revisiting old things. I could imagine someone buying the Mythic set and jumping right into these, rather than replaying the other 34 quests first and carrying those characters over. But now that it's in retail, that changes, and you've got people playing it for the first time and wondering "what is the proper order." Difficulty wise I'm taking what others have said and placing it around that same level. I don't have a big problem playing packs out of order, and with difficulty I'm fine with starting with a fresh party of heroes if it seems like they'll be too powerful carrying everything over. Yes, I agree that most Artifacts won't be lost (according to the rules, a lost/stolen artifact comes back early in the next quest, just like a dead hero gets replaced... sometimes I wonder if people remember that!), so in several cases you will end up with duplicates (which I'm not strictly against, to me this is more for the newcomers to a group while the old heroes have everything they could possibly need). Does it make the Artifacts less special? Sure, but for the overall experience, not necessarily for that player. Most of us homebrew, but some do not, so for them they'd otherwise "have to" go back and play that specific quest to get the item, which then it would seem proper to play the quests that came before that, etc. and not everyone is going to say "sure, let's sit down and play 34 quests... so then we can TRY this one). Again, easy to work around, but there are still the "Rules as Written" types who would see this as a real problem and not feel free to just jump in and try it out if that's what they're hearing all their friends on the internet telling them is the "right way." (side note: this is why I'm happy so many of us and even members of AH themselves are telling them DIY, don't be afraid, these suggestions are not set in stone, etc).
I too am about there being multiple parties of heroes (they've introduced enough of them you could image several sets of four setting off in different places, I agree).
The other stuff is a matter of tweaking the various difficulties present in the quests (see the errata lists and other fan suggestions on how to smooth them out). Going into shock in those couple of quests would be rare, but to me it makes more sense to use the ROTWL "unconscious" route if a hero were to run out of BP.
Many have ideas on how to improve these, like so many other things, so I'm curious to see what you come up with, good luck!