I did take a part time BEng degree course (1998-2002) at PolyU. Although the course was not in electrical engineering field but I think I may help you:
1) "72 credita" doesn't mean you have to do 72 subjects because the vast majority of courses "are worth"3 credits. If you finish one subject, you can get 3 credits. Some modules, e,g, design progject, carry 6 credits.
2) No idea.....sorry. However, I met a classmate who enrolled on a PT BEng degree course in 1997 and he was suppoed to finished the yr one study before 6/1998. However, I met him in my first year study (98-99), while he was still doing yr 1 for some reasons.
3) I just had a look at the EE website, course information was not available. However, if you look at
http://www18.polyu.edu.hk/e-prospectus/pt/prog_detail.jsp?prog_id=5397&prog_blk_title_id=423&org_id=5397 , you will find that you have to take some elective subjects that you will not be required to take all subjects.
4) If your exam results are not low enough, you will be awarded a degree with Honours. But "don't take it for granted" because I have a friend he may not have a Hons degree as he had a very low GPA.... If you don't have a Hons Degree, you may not meet the academic requirement of being a MHKIE