I'm certainly no expert but I think I can reply to this one (I'm sure i'll be corrected if i'm wrong
) I usually keep my secondary fermentation at the fermentation temperatures, after all, its still called "fermentation". The general purpose of a secondary is to: finish fermentation, allow clearing, remove the beer from the dead yeast. Conditioning (what I believe you are talking about), is the last step, at which you can do at serving temperatures. The "General" rule is 1 week in primary, 2 weeks in secondary and 3 weeks for conditioning. I condition my beer cold, this I believe allows it to clear even more.