[Rwp] Matching tempo, etc.

[Christopher-Mark Gilland]

OK, so, I know this has been done before with Reaper, but I need the 
specific 1 2 3 steps, and I need them to be as specifically laid out as 
possible, as admittedly, Reaper is normally not my go-to DAW.  I knormally 
admittedly use ProTools, however, this said, I'd be very! very! willing to 
do this with Reaper, if it's easy enough to do.

So, here's the deal.  I have a recording done by a young local indi artist 
who I am working very close with.  She has the original mix/song completely 
done, in fact, it's already even in ITunes.

She however wants me, being that I know all of the chords to the song, to 
make a remix basically keeping her original recording, but then adding 
things like electronic drums, note that the original song doesn't have any 
percussion in it at all.  She also wants me to add maybe an electronic base 
line, etc.  Basically, she just wants me to turn the song into basically 
something like a dance mix.  I don't plan to do any type editting where I'd 
be doing studders, or record scratching or anything like that.  I want to 
keep the song very very very true to it's original layout.  All I'm seeking 
to do is add some loops from very stem files I'll create through a different 
program than Reaper.  Then I'll just take those individual stem wave files, 
and import them into the project.  Making the loops isn't the problem.  The 
issue is more just knowing how in Reaper to get the average BPM tempo of the 
song.  The other thing is, when she recorded this track originally, she 
didn't use a click track, as far as I know.  She is incredibly steady, but 
it's not quantized, or anything of the sort, so inevitably, she's going to 
veer off and on the same tempo slightly.  Though it may sound a little 
artificial, I know, is there a way I could somehow import the wave file of 
her track, then make it conform to a certain constant BPM the whole way 
through?  Again, I understand that may make it sound somewhat unnatural, but 
that's OK.  She doesn't really want me to do this professionally, she's just 
wanting me to do it for fun, to see if I can.

This is always something I've wanted to do, to remix songs, so if anyone can 
work with me on this, I'd appreciate it!  By the way, if you're willing to 
work with me on this more interactively one on one, I can pay you up to $100 
for your help, although that would be the absolute most regardless how much 
time it takes.  $100 I could do, but no more than that.

Otherwise, please just write out for me the steps.

If it would help to hear the actual song, please write me off list 
requesting it.  I'd rather not make that download link public for legality 
reasons.  She told me I could send it to you all privately, she just doesn't 
want it floating around publicly.  If you're willing to help, and decide to 
do so one on one rather than e-mail, I could pay you via PayPal as soon as 
today.

Just work with me, and tell me what needs to be done.

Chris.