Very basic questions about rooting Kindle Fire

I'd like to root my Kindle Fire (2nd gen, I think - system version is 6.3.4_user4120720). I can't post a link to the method I'm planning to use, but a google search for "techhive how to root your kindle fire pcworld" will take you right to it.

My questions: Which version of the Android OS will I end up with when this process is done? Once the Kindle is rooted, is it then possible to install later (or the latest) versions of the OS, or does the device itself limit what can be installed?

The reason I want to root is that as certain web sites have become more complicated, the Silk browser has become pretty much useless. It's almost impossible to read the news any more. Pages bounce all over the place, or the browser crashes as pages load their nonsensical graphics and animations. I'm hoping that rooting will open up options for installing a better browser. In addition, my Kindle is no longer able to run the current version of Dropbox, which is important to me. And finally, it'll be refreshing to get rid of the stupid carousel!

Google Now always showing basic version of result after recent update

After a recent update of google now i noticed it is not giving any voice result, just a basic webpage. After scrolling to the end of the page it says, " You're seeing a basic version of this page because your connection is slow. Google optimized some pages to use 80% less data, and rest are marked slow to load" . and there is an option below to it which says "switch to standard version" but that applies to the currently loaded result only not "switch to standard version as default"

Well i would have understood if my connection was really slow but its not. in fact other devices connected to same network are showing normal results, the only difference between these devices is that mine is at jelly bean and other is at lollipop..