Reply to Preparing loops and samples for the S4

I have a lot of loops from sample libraries that I'd like to use in the S4 and I need some help importing them.

I've been using the browser I navigate to the folder and use the import as loop menu context. A lot of the time the bpm detected is wrong, especially for bass lines, so I've loaded the sample into a deck and then tried to manually set the beat grid. Then dragged the track back to the sample deck but it still won't play in time. Is this the right way to do it? Somehow there seems to be a copy of the loop in the sample directory as well as my collection.

So in short my question is, what's the right way to import and prepare loops from an external loop library?