Mine lasted four weeks. During that time we had rain on a weekly basis and 5 inches of snow. The deer licked it regularly after they found it (that was about a week after putting it down. I would recomend it for duration.

I would suggest putting it on a log or stump. Mine always last about a month and a half and it gets visited by deer and other game daily.

It really depends on where you hunt. If you look at the reviews of all the mineral and game feeds, some people have good luck with the stuff they put out and some don't. It doesn't hurt to try something but if the deer don't like it, they don't like it. It probably depends mainly on the deer population and health. If there are a lot of deer the chances of it getting eaten or good. If you hunt where there isn't as much to eat, chances are the deer will eat this. You can look at the reviews for an idea of what you want to get but the best thing to do is try it out. But I wouldn't get anything with a poor review. I usually go after something that has mostly or 50/50 good reviews.