which type pouch use for this skin barrier?

Any ConvaTec pouch (Closed type or Drainable) that has this same 1 & 3/4” Flange/Connector size snap-on coupling will work. There are many, many pouches that will work, it is not possible to recommend one.

How many does it bring ?

Box contains ten wafers. A wafer will usually last seven to ten days. At that rate a box should last about two and half months.

Pueden enviar este producto a México?

No, solo dentro de los Estados Unidos ...

What is the expiration date on the box?

I don't know, I am not at home so I can't look. But, as long as they are kept at room temperature, they should be fine for a very long time. They should not be exposed to excessive heat or cold...