Thank you for your interest! Now, let's get to answering those questions...

1. In this case, it would be separate regains, but that's related to how the summoning actually works: the item or creature being summoned is being reconstructed here in Maerchenhaft, so if there's a great number of items in a storage space, each of those would have to be recreated as well. So it's just getting into being larger magic! That's not to say that you'd have to only bring in one item at a time going forward, but for the initial regain just the 4D pocket and one item of choice within it would make more sense for how summoning works in game.

1a. Yes, absolutely! That would be perfectly fine.

1. You can include any reference to side content you plan on using where it has a notable impact on who you're apping, but generally speaking, it's fine not to when it's a loose basis for how things happened at what time, just that most probably did. Main content is most relevant!