True:  It means that someone or some group of persons is telling others only the bare minimum of information.

    Of course,  such a method can seriously handicap other people at a future time.

It shows a proprietory attitude (an attitude of owning information and keeping it mostly private). 

If I'm not wrong, "need to know" is a phrase used in the military/police force to classify data that requires certain clearance in order to obtain them. So when the author said "I like to keep everything on a need to know basis", I think he meant that he would like to keep his information secret from people unless these people require them for some official purposes. Hope this helps! :)

Great question.  Need to know is that a persons job responsibility requires knowledge of that information.  For example,   I was an officer in the Army.  Just because I was an officer with a security clearance, if I was not working on a project that required me knowledge of a fact I DID NOT have the need to know.  

With telemarketers they want to know all about a person to appear to be your friend when all they want to do is sell you something or take your money.   It is best to keep your information safe.   

I think it means that needs will bring inventions.

u know when you feel having lack of sth or require sth in ur life, undoubtedly do ur best to solve them and this requirement will expose u to a situation that it could help u to know the basis of that stuff throughout.

"need to know" basis.

This means; the information will only be given if you NEED to know it.