I am trying to build a web application which should use Laravel as a RESTful backend API and AngularJS on client side. I read all the other post on Stackoverflow about the issue
This is a half comment half answer, it got too long.
Matteo as you pointed out there are basically three different places you can do some sort of routing/redirecting with this stack. Ordinarily I haven't seen an advantage to doing the redirects at the Apache level, I imagine this might be more useful for localization or perhaps some sort of load/disk balancing. However you will have your VirtualHost configuration if you have multiple domains pointing to this address and you need to route those initial requests to the appropriate index.html (so if you consider this routing this would be my server side routing).
Generally speaking after that I rely on the Angular $routeProvider to handle client side "routes" really just mapping a URL to a view (possibly passing along some data).
I haven't gotten fancy with setting up a router in my PHP code to create a proper RESTful interface. In my particular case the data is being stored in a fairly abstract way and I had to do a fair amount of work in the PHP to get it organized in a coherent way, any straight ORM type solution wasn't going to work. This attempt has led me to consider options like MongoDB though since it should alleviate the workload necessary for doing the translation from persistent storage to client side and back.
Anyhow all that said I use $http to just make my calls from custom services to particular PHP endpoints that I need. My PHP folder with my scripts sits right next to where my index file is served up so requests from angular are all relative paths from the server root which keeps it simple. So they are physically "nested" so to speak or living side by side but the PHP code never writes any templates or affects the presentation it just gets data and serves it up (as JSON), so conceptually they remain separate.