[cflsystems]

MaxCDN allows you to either use their SSL or upload your own. The CDN does work with SSL. Of course if you are to use your own SSL it has to be for the CDN url.

The xCDN module allows you to enter both http and https urls.

As for whether you need CDN or not that would be somewhat debatable. It all depends on the amount of resources on any given page. CSS files are usually cached by the browser for so many days so once downloaded they are not requested again until time expires (unless your site forces download each page load). JS files are loaded every time so their size matters. A page with 1 image will load a lot faster than page with 10 images so in the case of many images per page you do want to have the CDN there.

You can test your site by making it http and using the MaxCDN you have - same page both ways - and see if there is any significant difference. Sometimes the CDN gives you so little advantage in load times that it is just not that necessary. But again whether you need it or not highly depe3nds on your site and contents.