I'm working under Ubuntu and I have
TeX Live 2015 installed. I need to know if it is possible to use
Kile, how to add a menu entry for it and finally how to run
arara on projects.
It is pretty straightforward. For example, here are the settings I use:
Then just configure a short cut of your choice, if desired.
Running Arara on a project is just like compiling any other project in Kile. If your file is part of a project and you've set the project up with a root document, then running Arara will compile the root document even if that is not the current file. (Whether this is what you want or not is, obviously, rather context dependent.)