You currently have the option to hide the results on the website and even to download the hidden poll view to powerpoint. I think it would be easier, though, if when I click to download to a powerpoint, it would automatically download both views instead of having to download the poll twice (once from each view).
Already implemented (see comments)
By hiding the responses do you mean the 'show instructions' / 'show chart' button that appears at the upper right hand of a live chart when hovering your mouse there? If not give it a try! If so, this button functions the same way in PowerPoint.
Polls embedded in PowerPoint access the web to generate the results, visual settings, and question. These settings are not saved in PowerPoint. So, any changes you make online will be reflected in your PowerPoint. You do not need to 're-download' slides after making changes.
Hope this helps!