Logic - New To Anything Non-pt, Soundcard, interface, etc... Options

[mixfisto]

I'm a songwriter/producer/engineer who has spent the last six years soley in Protools. I'm now focusing more on my songwriting vs. the engineering. I'm looking for software that is much more user friendly to write in. Logic has always been talked about to me but I have never really looked into it. This seems to be a great choice. My questions are:
-What sound cards are needed (and suggested, I'm running OSX.3.6)?
-Is there any other neccesary hardware?
-How compatible is it with PT LE?
-Are there any other similar programs that might be better suited for me (I write mostly pop-rock stuff, loops with real guitar+vocals, etc...)
Thanks