Which stock is which??

Don't panic.  Line up the stocks from tall to short.

You should have five stocks - one longest, two identical next in length, one shorter than those and finally, the shortest.  These are, respectively, the bass drone stock, the tenor stocks (2), the chanter stock and the blowstick stock.

Yes, the blowstick stock is the shortest.

Sometimes, the chanter stock has a "notch" inside the bag to allow the welt of a leather back to fit more closely into the tie-in groove.  This also helps to identify it.

Sometimes bags are incorrectly tied in with the blowstick stock and chanter stock swapped.  (In the two cases that I've seen, this seems to cause the intonation of the chanter to be really messed up.)