Hi to all the veterans here, would like to seek some advice from you all

I am a recent graduate from NUS, 2nd class lower in Economics(FASS). I have accepted a job offer from one of the ministries here, gross starting pay is 3K including NS increments. Under the MX12 scheme, salary range is $1970 - $5340

I would like to ask the following

1)Roughly How much are the yearly increments? Each increment equates to a rank in the pay grade?

2)How many ranks would there be, in for example, the MX12 pay grade.

3)What would the promotion prosepects be like? Promotion to the next pay grade, MX11?

4)Given that i peform average-ly compared to my peers, where should i see myself in 5-10 years' time?

Sounds like a little ambitious when i haven't started work, but i would like to plan ahead and give myself something to aim for, rather than just work and be lost.