Question about Remixing

thanks for the suggestions. i'm gonna look into both when i get back to working on this a little later

I don't think that is what the OP is about.  I am assuming (and I could be wrong) that what the OP is about is remixing songs that have been done by someone else and the music was all done to a click and that David is interested in doing a remix of that song.  Which involves working with the stems and adding in new material, taking out old material etc.. Creating a new piece of music if you like.
 
It is actually more fun and interesting to do this rather than attempting to do a remix of your own material or even a cover that you have covered.
 
The real interest is working with material that you have not heard before.  And doing something interesting with it.  Most of this type of material has been tracked to a click and what I suggest is actually the right way to go about it too.  Once you line up the beginning and the end of the music to your DAW grid and this usually only requires a very slight change to the original tempo then you can work with loops and stuff because they will in fact play real nice against the stems that you have imported.
 
Music does not have to be non click based in order for it to be good.  Some of the best music I have ever heard is quantised etc..  It comes down to how it effects you at the end of the day.  And music that effects you can be either very grid based or totally free.  It does not matter.
 
So David remixes are fun and interesting and quite challenging too.  The only problem with it is that it can take up many hours of your time and you will more than likely not get paid for it.
 
 

Yea like Jeff said, we're specifically talking about click based pop genres of music here that keep a steady 4/4 constant tempo time and never deviate... Unless of course you break apart the stems and start trying to play a new instrument to it and then it's like "what in the world tempo was this played to?" haha.
 
I haven't had a chance to go back to it, but I think the answer is going to be like he said, just figuring out an exact tempo, even if it's not an even number, that works with the beginning and end of the song and the rest SHOULD then fall into place. I had clicked along with the metronome and found it at 110bpm, but maybe its really 109.7 or 110.3. Something like that.

The other thing you can do of course is once you do have the tempo lined up at the start and the end of the tune then in the middle you may have to cut some sections and move them usually only very slightly or quantize the audio in spots to move things back onto the grid if you feel they are drifting.  I have found from experience it is better to move the audio around to the new DAW grid rather than the other way around as well.  Studio One makes all this very easy which helps a lot.