Bigger flame and bigger cut, not so fast nor precise but waaaay cheaper to run plus you can carry the bottles. Acetylene is really nice to use but propane is just easy to get about with. We use acetylene in the workshop and propane out on site. Some sites don't allow acetylene at all.
Not that far! Just a bit further away as unlike acetylene the heat isn't focused right by the tip of the primary flame. Been eons since i've done any oxy fuel cutting as my world rarely includes carbon steels these days and when it does it's usually thin wall tube so... http://www.youtube.com/watch?v=f2amO0T3vkQ It's an official Smith tutorial come advert so loads of safety stuff but covers what you're after.
I prefer propane, cheaper, IMHO it cuts just as well as acetylene, its just a different method ie. with acetylene the inner cone is where all rour heat is, for pre heating, with propane its in the outer cone, so hold your torch about 3/4" from the work peice when pre heating.
The Harris video on it is worth watching too, see the flame a bit clearer in that one. http://www.youtube.com/watch?v=cdvMNjD3pCE
And a brief bit on gouging/heating nozzles too.