Contrary to popular opinion you can add lean muscle mass while stripping bodyfat, but it's very challenging (at least for me).
I've lost 100lbs in the last 10 months and added some quality muscle (not a ton LOL) on my frame in the process.
Creatine is an ok supp, but it's primary contribution for me is water retention. I haven't used any creatine since I've started to lean out because of that very thing.