I took a look at the shop guide which was helpful as the shop is confusing as fuck. I did wonder though, the costumes provide no gameplay benefit right? As a F2P, I don't want to spend any gacha currency on things outside of the gacha. XD
No, skins are purely cosmetic. The ingame effects you might read about are just cosmetic too like visual effects during skills. Yeah as a fellow gacha player, best to resist the temptation.
Oh well that's something. Do any of the more common ships I see on here (eg. Texas x Lappland) have any canon backing?
Texas and Lappland are childhood friends or rivals depends on how you interpret it. Lapp's stalker like tendency does get interpreted as a crush so it does fall in subtext, arguably very subtext. There is more subtext for Texas x Sora at least on Sora's end since her whole motivation for joining Penguin Logistics and by extension Rhodes Island is to be with Texas for saving her from kidnapping. Schwarz x Ceylon also has, imo, strong subtext there. I'd advise looking up their lines and more especially, the chibi animation for Schwarz's Xmas skin. And then Saria x Silence, well canon is that Silence hates Saria but Silence's token, her feather, indicates possible past positive feelings, and Saria has one feather (so does Ifrit), indicating an emotional connection among them. Also, one of Ifrit's lines is basically just "Why are mom and dad fighting?"
And going off of that, what would be your evaluations of the main story, world lore, and/or character stories? So far the prologue and chapter one have started off with some interesting world-building elements, though I'm not a fan of the amnesiac self-insert protagonist and I'm wondering if the characters will get more depth to them.
Generally there is a ymmv on the main story as it does not get "good" until chapter 5 or 6 depending on who you ask. Imo, I liked it and the general direction it's taking. Yeah the world of Arknights is fucked and it' should not be a clear good vs bad thing. Like it does try to show the motivations behind Reunion and why they do bad things in world that hates them and basically has judged them to die inevitably. While it also shows that Rhodes Island is taking the positive outlook by trying to find a cure, it nevertheless allies itself with "enemies" of Infected since it needs to maintain a neutral stance and not get powerful enemies. As for character depth, I think the main focus is primarily on the main protags. Sadly the other characters that show up do not get much and you'll have to rely on actually getting the characters and reading their profiles. And yeah seems Doc is just self-insert as you play as a passive audience who is just watching the stories unfold. There are spoilers regarding the Doc's past that he may be or was something more but whether that plays into the present is doubtful. It will probably just be used to reveal more about Kal'tsit, Amiya and background lore. I doubt the Doctor will be an active protag of any kind