metering - How do I meter for film photography?

I am using Leica M6, in the manual, it said

Expose color negative films for important middle-tone areas and never fear overexposure

Expose b&w film for shadows and develop for the highlights

1. 
   

   For the middle-tone areas metering, I assume I should meter using the centre of the frame in an area which is not too bright, and not too dark first, then move the centre back to construct the photo, am I right?

   
   


2. 
   

   For b&w, I assume it mean to meter on the shadow right? But what is the meaning of develop for the highlights?

   
   


3. 
   

   For the overexposure, should I keep it consistent for the whole roll of film? e.g. always 2-stop overexposure

   
   



4. 
   

   Should I also overexpose for b&w film?