Re: Detecting bpm in logic for audio files.
Steve H. goes into some of the many beat detection/beat mapping options in his tutorial Logic 304; Logic TNT 3; chapters 31 and 32. This method, I believe, can be used with any audio file, whether there is tempo information on it or not, or whether it was originally recorded with a click or not:
And also, another option not mentioned above that's good for tracks with varying tempos, from his Logic 201; Steve H's Logic Master Class; chapters 3, 4, and 7.
Being a little old school in this regard, I personally like to estimate the tempo by listening, and then apply a click to see how close I am. I then adjust accordingly, (it's interesting how many tempos wind up going out several decimal places, like 107.0652, for example) or beat map if the original performance wasn't recorded to a click. Using Rounik's suggestion of using the 'Detect Tempo' function will usually get you close, and then you can fine tune from there.
However, take note that the above mentioned chapters from Logic 304 shows how logic can find transients and beat map automatically. Pretty cool!