In general, I prefer conversations about specific articles to be held on the corresponding article talk pages instead of here, so that other editors can follow them too.
If you are referring to a particular edit, it is best to use a diff link.
I usually reply here. I am often working on several things at the same time, so if I haven't answered yet even though I am online and editing elsewhere, please have some patience - if it is really urgent, prod me with a follow-up message.
I can often be reached via IRC, too (HaeB on Freenode).