i don’t like ableton.
if ou start i recommend something like fl studio or reaktor.
if you want to record something ou shoudl try cubase or nuando.
it depends on your and your likes.
i started with FL Studio and i’m still using it.
it’s simple, but powerfull if ou know how to do it!
Logic Pro is ,for me, the best program. Logic is more a producing program but you can use it for your not live performance. If you looking for cheaper look for MixMeister Studio its perfect for arrange mixes.
I used Audacity for cutting out some stuff from a mix before. It can be done. If you’re cutting out something just make sure you always cut at a consistent part of the beat. I like cutting at the attack of the envelope of the beat. So there is a free option. No BPM detection that I’m aware of and may take a little longer then with a more powerful production software.
I also use Logic, but looking in to Ableton when i have some spare time to try the demo out, as it seems to be the industry choice for live performance.