Is there a way to Match Aspect Ratio at one time for all photos on the timeline (as opposed to opening the Event Pan/Crop and matching each individual picture)?

Yes: do it on the first photo, make Copy.
Then select the rest of the photos and Paste Event Attributes.

Bot probably you will see, that nudging a little with the cropping on many a picture gives a much better result - i.e. a few milimeter up or down changes the perspective of the photos substantially - and also if you have some similiar photos in a row then some nudging will prevent hopping of i.e. the horizon or other fixed things.

If I do match output, it 'blows up' my picture; the other does nothing.

However, if I pull the corner handle out, it reduces the size so it all fits. I thought I had tried this initially but I probably pulled the handles inwards thinking I was reducing the size when in fact it was making it larger.

I'm just curious why I'm having this problem now. I don't recall the problem before but that could be that I had different sized pictures. My portrait pictures in this version all have the tops/bottoms cut off. Movie Maker, ulead, Nero, all the other programs I have that have a 'slideshow' function keep my picture at its correct dimensions and don't cut anything off. Why doesn't Vegas do this automatically?

Thanks. This worked. Sony .. you need help in getting a better 'help' with the program.

Take a lesson from Corel PaintShop Pro -- the help is great and then they even provide a training video disk. For a program I paid $40 for and that is 'almost' as good as Photoshop (costing 15 times as much) . they have my business for life. For Sony Vegas and DVD Architect I always have to go to the forums and scan for what seems like days to find an answer -- the manual I downloaded is the same as the one I got printed and provides almost no information that I can use once I got into the program.