How to Save All Google Presentation Slides as Images

There is a Google Slides add-on for this: Slides Toolbox.

It allows you to select multiple photos at once from Google Drive and imports them each as a new slide.

No idea who the developer is but it works for this task, it has other features I have not tried.

When you present a Google Slide on the web, a task bar appears on the bottom right of the presentation (NOTE: Not in the presenter view window but on the actual slide window). There is the option Pointer which you can to point at stuff (obviously) but you cannot mark it up. Google is considering to add this feature but they haven't launched it yet.

Alternatively, there is a free iPad app called Notability which allows you to ink on presentations. This app is available in the App Store.
BTW: You have to convert your file to PDF in order to open it in this app.

I hope this helped you answer your question.