I have used either Excalibur or Ultimate S to get the pictures on the timeline, set duration, and apply both Transition and Pan and Scan effects automatically.
THese scripts save a lot of time and effort and are well worth the investment.
As to which one you would like better both have fully functional trial versions. I prefer Excalibur simply because I have been using it for two years. Ultimate S was a great program also.
Depending on the subject you may want to go with a lengthy full screen or have two shows going at once. I did one earlier this year with 700 pictures in it and the audience preferred watching the full screen version. It took about 30 - 40 minutes to watch the full thing. I found it boring but I was preparing the video not buying it.
You can also just build this manually, and use the Match Aspect script, but that won't give you pan/scan. You can get it at: http://www.vasst.com/resource.aspx?id=8d78eeda-a354-4898-973d-52d5ba2e1946
Aside from the fact that Ultimate S can give you pan/scan, it also will reduce interlace flicker, match to beat markers/music length, insert auto transitions that you can save/choose/randomize. There is a video tutorial on the site if you want to watch it.
There is also StillMotion, for about a quarter the cost, which does everything I just listed above, but has no other functions. It's a slideshow-only tool for the most part.
Either tool can build all the motion/transitions/timing/aspect ratio from the Timeline, Media Bin, or Windows Explorer.