Easy root method - upgrade or not

Hi,

I have a fresh , not upgraded Galaxy S6 Edge in its box.
Currently I use my S5 rooted without any issues. As I like to use my phones rooted, I'd like to root this one as well.
But I am not sure which root method is easily applicable with minimum limitations.
For example, I need to use Samsung Allshare cast dongle and it needs original recovery image.
So I prefer to root without recovery change , or if I have to change recovery, I'd like to revert it back to original.

So, how should I root my S6 Edge ?
And, as it is not upgraded yet, should I root then upgrade or upgrade then root ? Which one first ?

Thanks.