does all that.
All your effects are done in real time as you play the sound. 32 or more tracks of them (Ardour has no actual limit) Easy editing, seamless joins, full automation on every parameter if you want it. I've used both Ardour and Audacity: there is no comparison. I use Audacity for quick trimming and normalization of stereo material recorded on a pocket sound recorder, but anything more complicated gets done on Ardour.
You can argue about Ardour vs. Pro Tools, but basically they do the same kind of job. Many audio professionals use Pro Tools not because it's better than anything else but simply because if you ever send your work to another studio or get another engineer to work in your studio, that's what they'll expect.
Incidentally, Ardour also works on OSX and Windows now, but it's better supported (because more widely used so far) on Linux.