Hi there, you should check up Singapore Polytechnic's entry requirements for NITEC Holders.
GPA is obtained every semester, whereas CGPA is the cumulative one obtained for all the semesters. The higher the GPA the better. As different subjects have different credit units, the GPA every semester may vary on your performance on different modules.
Your awards and testimonies will add on to your portfolio which may be taken into consideration when you apply to SP.
Good luck =)