currently serving NS, and i have passed the selection test.
Basically, the selection test is about 3-4 hours. The selection
test i took was split into 3 different sections. Namely, modelling,
designing and appreciation. and each of the sections have to be
completed within 1 hour. The entire course is 5 years long,
straight to masters. 1 year of working attachment seems to have
been removed recently. I believe its all up to u whether u can
excell in this field. nothing much to do with the uni as there is
no clear cut right or wrong. Portfolio is required only for poly
students entering archi course or your results are botherline as i
have been told. Well thats for NUS. All the best in searching for
your desired course and do not regret your decision. 
