How to scroll between photos using arrows?
The way I do it (and there may be others) involves just the Finder and Quick Look.
I set the folder of pictures to list view in Finder, select the first picture and press the space bar. That will open the Quick Look window viewing the first picture.
You can resize the Quick Look window at this point and/or just use the arrow keys to move up and down in the list of pictures to display each one in turn.