Hi Vito,
I'm not sure of all you're asking. The reverse switches should be generally available. I bought one for my NG3 from a regular parts house in the US. I suspect pretty much all the Renault trannies of the time used the same switch. I noticed that r.d. enterprises (
http://www.rdent.com/) lists the same switch I got for my NG3 for all late S2s and TCs. You might look for a Renault Fuego switch.
The brake switch is under the battery and IIRC it is connected to a relay under the dash - but that may be US cars, only. In the US, the same light works the brake and turn signal lights in the rear. I wanted to use the red/yellow/white European lams so I separated the brake circuit and just used the switch activated by brake pressure.
I hope that helps a little, anyway.