1.DMG provides versatility in terms of job nature, mobility and opportunities to go for higher education like Ph.D. in Economics or Public Policy. One can do good for the country at many fronts from properly administering a city to making energy or environment policy etc.

2.For PSP: The uniform attracts one as well as the ability to provide quick justice to people. It is the enforcement wing of policy/judicial decisions so one can eliminate many crimes and social evils blah blah.

My reply would've been that I was impressed by my uncle who is a PSP officer and wanted to do all the good things of (2) in uniform but after a detailed study of every group I came to know that DMG is better for me due to 1.

1.Mode of Preparation:
Went through the main definitions and headings. Read stuff only if it required revision and trying to understand the concepts I skipped for the written.

2. I considered the study of subjects I chose more important for my job as a CSP officer than the ones I studied for my engg degree. Plus most of the math/physics topics in CSS syllabus weren't the ones we studied for our degree since we study stuff from application point of view rather than doing the proofs n all in B.Sc.

3. I had a job in Telenor which was financially more attractive but I gave that up for the prestige and status of a CSP. So that's how I prioritized the money and status. Yes a childhood dream and desire to serve country also had something to do with it. I was eventually going to do it so I didn't want to lose sight of my ambition for a short term gain.

4. No clue since I didn't get the question

__________________
Whatever you do will be insignificant, but it is very important that you do it.
-Gandhi