nouns - people are/is: which one is correct?

I have been confused for so long about the plural and singular forms of "people". I want to put an end to this confusion.

What is the difference between these following expressions, and is it correct to use these expressions in both their singular and plural forms?

1. 
   

   • "The German people are not warlike"

   
   
   

   • "The German people is not warlike"

   
   

(As in "The German people is no warlike nation. It is a soldierly one, which means it does not want a war but does not fear it....")

2. 
   

   • "People are funny"

   
   

   • "People is funny"

   
   
   

Here I suppose that "people is" referring to a population/community: "the German people is not warlike" = "the German population is not warlike" and "People is funny" = "population is funny".

Is this correct? If it is correct, then what does "people are" mean?