Let's see, in answer to the questions raised above:

PhD, MA, BA, BSc, City & Guilds HNC & HND - quite a marked "degree" in attainment level covered by the above, irrespective of where, or when, obtained. The one thing that is common to all is the ability of any particular student to clearly and accurately demonstrate to the examiner his/her knowledge of the chosen subject by putting their thoughts down on paper in the form of answers to examination questions and through work undertaken throughout the course of their studies. In general, therefore, the ability to write and to express oneself, clearly, correctly and accurately is extremely important.

Not all postgrads are unemployed, or unemployable.

Those with existing qualifications from years past - carry on as normal.

No.

Finally, in general; No; No & No.

Your basic intelligence test I would imagine relate to what is called "Common Sense" - That has nothing to do with formal education, individual quotient of it is derived from a whole rake of circumstances and conditions, one of which is from experiencing life and learning the lessons that life teaches us.