Re: Adjusting tempo for audio file...
If you mean can you time stretch an audio file... sure:
The simplest way is to option drag the right boundary of the region. Instead of resizing it you will be time stretching it.
Alternatively, open the audio region in the Sample Editor and choose Factory > Time and Pitch machine.
Do keep a backup of your original file.
You can turn it into an Apple Loop - best to find the tempo of the file, convert it to an Apple Loop and then make it follow the tempo of your project.
There's lots of ways to do this - and even more in Logic 9.
You've got access to the subscription I think? In which case check out the Logic 101 videos 42-51.