What version of Premiere Elements are you using?
With the new version 8, you can change the duration of all stills already on the Timeline all at one time as well as apply the default transition to all the stills on the Timeline all at one time. In earlier versions, once the stills are on the Timeline, it is one at a time changing the duration of the still and application of the default transition. More information on that if you tell me that you are using Premiere Elements 8.
In the earlier versions (like 4 and 7), you could change the still image duration for all your stills BEFORE THEY WERE BROUGHT INTO the Media Panel. See Edit Menu/Preferences/General and its Still Image Duration set location whose units are frames (so in a 25 frames/second system, 1 frame = 0.04 seconds...the frame value allowable range is 1 to 1000000 frames.)
You can also use Create Slideshow to take the photos that are in your Project media panel and turn them into an animation (assuming they're already in the right order).
To do this, select all of the photos in the Project media panel, right-click and select Create Slideshow.
In the Slideshow option screen, set the duration for each photo to 1 frame.
However, I started with the Edit Menu/Preferences/General route for now since the Create Slideshow route:
a. puts the stills on the Timeline in a video like format (that is, grouped), no longer single stills
b. allows for its use in these "all at one time" procedures for either image duration or default transition and not both.
I was saving all that for another time if necessary.
That's teamwork, Tony!
One comment on that Duration: since human "persistence of vision" * is ~ 1/30th sec., that is kind of short. For most "stop motion" work, I've found that 3 Frames at 29.97 FPS works very well. Now, if you are looking for fluid animation, and the change in images is slight (like a Video @ 25 FPS), you should be OK. If the images change much, you might want to investigate.
If you are Importing these stills into PrE, you will want to resize them, in Photoshop, to very near your Project's Frame Size, before Import. Your quality will be improved over letting PrE do the scaling and the overhead on your system will be cut down. This ARTICLE will give you tips on any resizing, if you need to go that route. If you have created the images to size already, you can disregard that article.
* Scientists have pointed out that it is not really "persistence of vision," but it's commonly called that.