Yes, but the "problem" is, that it's worded "... or other entryway" and the list of previous "entryways" already include a chest, which is clearly a container. So a box with a lock isn't obviously too big of a stretch, isn't it? A box with a pile of papers inside it? Well, that's basically a book with a cover that has a lock on it. I guess what the designers were trying to describe here was a "lockable thing you can open". Ie you can't Wizard Lock a pile of papers, but if you had a way to put them inside something with a lock on it... ;)

As usual, the description also includes the ages old "... or other" -clause which causes all kinds of questions and in the end leaves the decision up to the DM. I mean a "chest" isn't any less of an "entry way" than a locked book cover, covering a stack of paper.

The Sage Advice answers only the question whether the undead created can be destroyed ("un-animated") by a Dispel Magic. It doesn't comment on whether the control effect can be dispelled from an individual undead or the caster himself. (" Casting dispel magic on the creature can’t end its mockery of life")

"premature death would be very inconvenient" - well, isn't it for all of us. That aside, sounds like the character is heading in the right direction in life; Hell / Abyss / lower planes / anguish / damnation / all of the above. :D Edit: as ghould has been ruled out, has the character thought about vampirism? Isn't that more of a "seamless transition" than being dead and raised as a ghoul?

After the third time the PCs would probably be better off by using the bags of holding on themselves... (This whole thing has a "Benny Hill ending" -wibe to it.)

I would say communication by a spell would help immensely while trying to get to an animal's good side; you can find out what it's needs and fears are, and work from there. Is it hungry? Offer it food. Was it mistreated by the giant's? Offer it kindness and safety. Speak with animals would allow the caster knowledge which otherwise wouldn't be available, or could only be guessed at. (All, or course, depending on the animal's memory capability / intelligence.)

@Theik there are actual earth religions that have their followers doing that for mundane, daily things - so how would it be far fetched that in a fantasy world, someone who has actual proof (been given magical, divine powers, maybe encountered their avatar, etc) of his or her god existing, actually does it? Just saying; gods are more real and zealots are more... zealotous (is that a word?). Have a nice day, Tyr willing. ;)

I think, in a case like these, there should be a clear group-wide decision on which way people roll the dice. Either everyone rolls in secret, or nobody does (unless it's a question of a roll affecting another player in some way, like bluffing, stealing from them, etc - naturally).