I never doubted that she survived, and I do remember that the anime made it pretty obvious that Maryrose survived, I just assumed she peaced out from the island.
Same here, I saw the anime first and maybe that makes a difference, but it seemed pretty obvious to me after a couple viewings that she probably survived, and that the real surprise would be how and when she came back and what she was doing in the mean time, not "if" she came back.
And if I had any doubts from that, then the manga cleared them up - the manga highlighted a couple of hints that Kate had set up a way out, which the anime didn't. And, I'm pretty sure that Anthony at one point more or less told Kate that he knew she'd helped Maryrose and Rosemary escape, complete with a diagram of how it worked - I can't hunt for it now to find the exact chapter, but the buildup to his was a long time coming, and telegraphed pretty clearly.
And I gotta admit, I didn't expect her back so soon, good to see her again.
The two comebacks I did NOT see coming were poor Rum and Shirley (it was a very pleasant surprise to see them back again!), and... well, no sense in spoiling the other one, I'll just say that I forgot all about two characters that were there almost from the very start, and about what happened to them through all the twists and turns and skullduggery the story has gone through, and that those two characters return not too long after this chapter.
I am hoping for Edward and his crew to have a full redemption arc, even if he's still an ass.
Same here, though Edward grew on me before I finished the first season of the anime... he seemed weirdly likeable, for an obvious anime villain, I sort of found myself cheering him on through the Manga to this day, even knowing that every scheme he comes up with is bound to fail, and every time, he gets that sort of deflated, defeated, back-to-the-drawing-board sort of thing going on, but never really gives up - he's sort of like a Wile E. Coyote to Kate's Roadrunner, no?
It's hard not to admire his ingenuity and persistence, in spite of over-complicating every plan, almost as if he's deliberately setting himself up for failure. And of everyone we've been introduced to in the story, Edward seems to be the one character to have gotten the most important thing right: NOBODY should be trusted in the Shadows House.
I like his two sidekicks too - I'm not sure if they'll go through a redemption arc or not - Eileen sometimes seemed a bit ambivalent about her relative freedom from the house, but I don't think I've ever seen either her or Gerald give any real hint of villainy otherwise, so a "redemption" arc would be almost too easy there. Honestly, Edward, Eileen, and Gerald actually seemed to mellow out quite a bit once they got away from Shadows house, and by the time we actually see them again in the village, they almost come across like they could have been the heroes of their own story, if things had only gone a little differently, or given more time away from the scheming and backstabbing in the house.
But, we really haven't seen anything about Edward's backstory before the Shadows House yet, he seems to show a few hints of hiding a tragic side every time he has some quiet time with his only friends, and something tells me he's another one of the many characters in this story that ends up being more complicated than they seemed to be when we first meet them.
After all, that seems to be the running theme for this series: you can't really trust who anyone seems to be when they are first introduced, I think just about ALL the characters in the story, even the background characters, reveal hidden depths later on, and few of the antagonists have turned out to genuinely be the villains we were set up to expect them to be! (Thinking back on it, the only unambiguously villainous characters we've met so far seem to be the Grandfather, Sophie, Ryan, Anthony, and - of all characters - little Maggie, the wall-flower, in one of the most shocking plot twists of the whole story!)
Anyway, that's my take: Rosemary and Maryrose always seemed destined to come back for the grande finale - it was practically written into her whole characterization and dialogue! - and Edward never seemed quite comfortable with being a villain, while his only friends (or "henchmen") actually seemed at worst to be harmless, in the greater scheme of the house....