Guild Wars 2

I have Weaponsmith and Armorsmith as my two crafting professions. When I slay a monster and it drops an item that i can use to craft, it shows a (25) and it will say weaponsmith and be green or like armorsmith and be red. What does this mean, can anyone explain this to me, the numbers also?

If the number is green, it means you have that craft at a high enough level to use the item. If the number is red, it means you have that craft, but not high enough level to use that item with that craft. If the number is white, then you do not have that craft active on the character at this time.

Also will i be able to craft higher level items as my craft levels up? do i have to discover the higher level weapons and armor

http://www.guildwars2-crafting.com/crafting-guides/
This is a great guide. If you dont want to follow it, it is still good reference for your questions.