When copying content from another presentation into a different presentation template, is there an easier way to reformat the text/pictures in each slide without having to go through each one individually??

You can use the master slide to achieve this. Once you have imported all the slides you want, simply right click on the current design template on the task pane under design templates, and select Apply to all slides.

Either that or you could go to the master slide and delete any of the ones that you do not want to use.