Unless you're purging your secondary with CO2, you always want to rack while the yeast is still active so that continued fermentation pushes the air out of the carboy headspace. At home, I typically rack to secondary as soon as the krausen has fallen.Speaking of hops, I have to dry hop one ounce. Should I move to the second fermenter and dry hop now while there may still be some yeast activity left?
Yeast activity shouldn't affect dry-hopping. At work, we dry-hop at, or very near, terminal gravity.