I am going to produce a slideshow from scanned photos. I will burn to standard DVD when completed.
Which sequence preset should I setup for my project?
SD DV is the easiest.
I would also do most of the Scaling outside of PrPro, in say Photoshop.
Though PrPro CS5 has improved the Scaling considerably, if you have many overly-large stills, you will be pushing around a bunch of unnecessary pixels, and this does take resources.
This ARTICLE will give you some tips on automating things in PS.