Those are lot of questions fired in one single post please ask some questions separately for you to get perfect answers. If I just stuff all these answers in a single paragraph then you will not read nor you will understand even if tried to due to complexity .(lack of rep forces me to keep this which should be there as a comment to your question)
So my humble request is to first check in the search bar for you questions if not answered then ask them separately.
Here I will be answering only the main questions to get you started .
After you have installed the tor browser your need to configure it properly.In order to use it to open blocked /censored content.
For simple browsing you can directly open the tor browser(through the browser bundle which opens up by connecting to tor automatically) but if you want to open mail clients like Gmail you might or might not be able to open it because Gmail allows login only through Cache enabled browsers but in this case your browser will have max disabled settings in order to browse anonymously to a great extent.
And coming to get rid of other browsers my suggestion would be no. In case you have not configured properly or cannot open some site which Is open generally (not blocked) then your other browsers will come handy. So please always make one browser as backup.
As last resort for you still not following the above follow this page