What are the sizes of the bags created with tailoring in MoP? and what are the mats (or other requisites) to create them?
There are no Windwool bag recipes.
There is an Imperial Silk bag recipe : Royal Satchel has 28 slots. It requires August Celestials faction to learn, and 12 Imperial Silk to make. It takes 480 windwool cloth and 12 days, or 300 windwool cloth and 36 Spirit of Harmony to make those Imperial Silk.
There are no profession bag recipes at this time.