I suspect you are in an existing file that has some non-default settings.
I suspect the "play symbol" is an arrow-shaped bullet for a bulleted list.
Regarding "as soon as the last letter appears", PowerPoint doesn't work that way. By default, a slide appears and then exits as the following slide appears. I believe you are working with a file or template that already has some animations and customizations set, or maybe you set them by accident.

Try clicking the New button and making a new file from scratch. I also recommend looking at any of the many free tutorials on the web.

Save the file as a PowerPoint Show (pps) to have it open into SlideShow view when the file is double-clicked.