guild-wars-2
The bag slots that can be unlocked (for 400 gems each, currently) are just for the character that purchases them or you only have to unlock them once for the account?
Also related, I assume that unlocking storage in the bank is at an account level, but I'd also like to confirm this.
If you look at the official wiki for Shared Storage vs Account Storage there is no mention that Shared Storage has a collectables area. It was not present during the beta so unless it get added for launch the answer is no. However, you can put a collectable into shared storage. It just doesn't have a separate tab for it and counts as a space used in your overall storage where is is a separate item in your account vault.
Just confirming post-beta that Guild Storage does not have a separate area for Collectables:
So two things:
First, every character can learn every crafting discipline. You won't even lose progress. The catch is that you can only have two active discipline at once (as in, can craft things with them), and it costs money to switch between them, based on how highly skilled a discipline you're switching into. (If you switch in to a discipline you have no experience in, it's free!)
Second, most untradable items are, in fact, account bound, so you can freely store them in your bank and remove them. I assume the actual Legendary Weapons will bind to a character, but the materials can be passed around willy nilly.
But Crafting in Guildwars 2 is very much its own part of the game. Crafted gear is equal to gear earned from any other number of options, and is not inherently better. The only real "perk", if you want to call it that, comes from convenience.
Best Answer
Bag Slot Expansions apply to the character, and Bank Tab Expansions apply to the account.