I know this is late, but stumbling a lot of good questions and found limitations of Connect. This being one of them.
You can preview it in browser too. This is behind multiple steps, so I recommend only using it to finalize design and tweaking settings. You can open survey from website, where you see all your surveys. Note that if you start survey creation in Connect, you need to publish it in order to view it here. Same goes the other way around if you want to start designing in web designer, it becomes available to Connect only after publishing. But Publish is very confusing way to describe whats happening as its not shared and is only available to you and the admins of your organization. So essentially its still private. Once survey has been published, you can open it to browser with the chainlink icon that appears when hovering over the icon:
In order to update survey from XLSForm to web view, you first need to save XLSForm, allow Connect to update survey, publish it (allowing any major changes) and then refreshing the browser view.
Simple and quite doable alternative function would be to allow Connect to launch browser and view local files in browser. Many website authoring tools have this functionality if they don't have imbedded web rendering.