@god of war & yasir khan durrani

i passed SPSC exam back in the year 2001 to join excise & taxation dept in the capacity of inspector.

syllabus and past papers of CCE available at Urdu bazar

cant comment on scoring subjects as CCE is not regularly conducted.
i can share my personal experience that commerce comprising and economics are not scoring ( i had them in 2003 CCE and secured less than 100 marks in each ) however islamic history is scoring. ( again it is purely based on personal expreince. others may have different opinions according to their knowledge , experience and understanding.

ppl opted for DDO-R only because they were already on jobs and they considered DDO-R to be the only category that might attract them to leave their existing jobs

DDO-R and SO( secretiate group ) are more career oriented jobs comparing to other catogories.

about the time span b/w registration and examination , God only knows exactly when the exam would be conducted

generally 4-6 months time is given. ( CCE 2008 was announced in Jan 2008 and exam was to be conducted in May-June 2008 but they were actually conducted in March 2009 )