We are going to dvd with footage filmed on canon 60D at 24p and edited in FCP 6 - What would be the best Timeline settings and also final render for dvd?
Transcode to, edit in, and then export to HD. Once all that's done, take the HD master file and convert it to SD for DVD. While DVD is standard def, there's no point in editing the whole thing that way. Keep a master file of the HD edit, and if/when you need it in HD later, you've saved yourself a whole lot of extra work.
You can edit through the whole thing, export at current settings, and burn to DVD, all in 24P (23.976).
Since FCP6 doesn't have ProRes LT, use another flavor of ProRes if your system can handle it. Otherwise, DVCPRO HD is a viable option. AIC is kind of a last resort.