My reading of those skills are that they are seperate (sub)skills and need different magic items.
You cannot use craft:carpentry to build a metal sword for instance.
Are these skills similar enough to give a discount when pricing a magic item with say three craft skills is another Q you will probably need to ask.
I suppose an item could have a bonus to all craft skills, but it would be very expensive (relatively speaking) compared to a single craft skill.
Also any INT boosting item will boost crafting ability.
An item with +3 to all charisma skills is 4500 (500*3^2) per SRD, so I think one that helps all craft, perform, or profession skills would be less.
Knowledge skills are different because they're all listed seperately, even if they are under one skill (Knowledge). There's no class that only lets you take Perform: Mime, or Craft: Basketweaving.
My reading of those skills are that they are seperate (sub)skills and need different magic items.
You cannot use craft:carpentry to build a metal sword for instance.