I'm on the Fast ring and am running the current Build on a Gen one Surface Pro and I can assure you what you've been told is Bullcrap
Taskbar cannot be disabled. You can select to "Autohide" the taskbar just like you could in every windows build since Win 98. However Autohide does not work well, it is not touch sensitive like the Charm bars were here is the key
you can't manually swipe to make it appear and then swipe to make it disappear it stays on and turns off on it's own quirky timer that you can't adjust, it stays on screen to long and doesn't come back well when you need it. This is not a currently viable option because of how buggy and intermittent it is.
Their is ZERO way to Surf the Web right now in Win 10 WITHOUT on screen Address bars, Tab Bars, Navigation Bars etc. Maybe you could install Firefox or Chrome and disable all these elements but as far as IE or Spartan their is absolutely NOT a full screen web browsing mode that acts like Metro IE did in Win 8.
Seriously watch this video as someone posted above, this is Win 10 10061 on a tablet. Notice all the Taskbars, Address bars, Tab bars, Navigation bars etc. This is what it is right now.
https://youtu.be/W93cq713X7U