Yeah, in theory there’s an in-game encyclopedia to help with resource info, but in reality you’re better off searching the wiki for that stuff.
Cetus has a quest that will get the basics of what it’s whole deal is, from a lady to the west of the market when you come in, which should help with understanding it’s own internal systems and the like.
Most blueprints are in the shop terminal, but there’s no real way to just like, browse for some new guns or knives you might like, as far as I know. If you see someone with something nice in matchmaking, check what they’re using and search for it, it might have a blueprint.
Fusion is leveling up mods in the terminal you get in the tutorial quest, it’s a weird name choice that makes you think it’s something it isn’t.
Basically, it’s a game that’s designed, and continues to be designed, for people who are already in deep. It’s a problem a lot of ongoing games really should address better to be honest. If what it’s putting down conceptually strikes a chord though, or even if you just wanna see some baller hard sci-fi story stuff, it’s well worth the investment, because it’s absolutely got eveyrthing you want if you’re willing to take the long drive.