Can I craft Legendaries as a Cook/Jeweler as well?
Each of the legendary weapons require two gifts that you make with a crafting skill of 400. These gifts of craft are account bound, and thus you have to have the specific ones needed for the legendary that you want.
Refer to this http://wiki.guildwars2.com/wiki/Legendary_weapon for the needed crafting skills for each legendary.
But just note that getting some crafting skill to 400 will be the least of your worries on your journey to legendary weapons that might take month upon months of active playing to reach.
After reading about Legendaries, I agree, getting a profession to 400 is going to be “baby step one”.
Probably not. Legendaries have the same stats as exotics, they just look fancy. As a jewel crafter and cook you don’t actually have anything visible so it doesn’t make much sense.
Though I guess it would be nice if they could create something visible even if it’s just town clothes or some sort of back armor or something.