ORIGINAL: Alsatian
(1) How do you place these packages? Are they teethered to anchors to be just under the surface or are they intended to float on the surface, the teether simply keeping them in place?
I used them for several seasons. And with pretty dang fine success. I have a Higdon Pulsator and a floating Mojo that pull the job of surface ripples now... but those things work pretty good for $15.
You can set them up one of a couple of ways. You can tie an anchor directly to it, and that works pretty good. I hunt mostly in tidal creeks and other places with current. What I did was take a feeder butt decoy and run about two feet of decoy line off the butt (which was anchored itself) and attach the shaker puck to that. That way, the motion was coming from very close to a decoy. Worked like a champ.
(2) I see mine, bought at BassPro, are marked made in China. How long can I expect these things to last before they break? Any special precautions I should take to prevent water infiltrating the threaded coupling?
The issue isn't really breaking... its water and especially internal condensation (the beer can effect). If you are good at sodering and rewiring small electronics, you can keep them going a long time. If you hunt as hard as I do (20+ mornings a season), I could usually get two seasons out of them. Some work longer than others.
(3) Do they work to bring the ducks in?
Oh heck yes. Especially on super still days where its very hard to get ducks to work tight. I think its $15 well spent dollars. I usually ran 3 or 4 of them... one per about three or four decoys.