Yes as a cadet flying instructor for SFC your training is sponsored, in return for a bond.
Subject to good performance, your entry into one of the SIA companies (after you complete your bond) is almost sure. Note that you have NO control over what they offer you - ie cargo or pax. But they will tell you first, from day one, where you will go. So if you have an extreme objection to either, then consider this situation VERY carefully.
You appear NOT to have taken my advice to do research. You are asking questions that reveal your uncertainty, even confusion, as to what you want to do with yourself 8 years from now. Only you can help yourself in such a situation, as opposed to asking for advice on how to do something you have decided on. This is the last time I will spoon-feed you.
Read these two threads at the very minimum:
Terminology:
http://www.pprune.org/forums/showthread.php?t=134076
Advice for wannabes:
http://www.pprune.org/forums/showthread.php?t=131649
In short, if you are SURE you want to be a commercial pilot:
1. Finish NS.
2. Go to university. Full time, not this part time nonsense that YFC is offering you. DO NOT be cowed by pressure from them. It is natural that they want to see returns on their investment. YFC is basically a recruiting ground for RSAF. They are not dishing out PPL courses for nothing. Since you are unsure about what you want to do, university time will buy you some job insurance.
3. Either:
a. Look for work then wait until 26, and apply to be a cadet pilot.
b. Apply to be a cadet flying instructor to bide your time until you are 26. If you are already 23 when you finish university, or have no passion to teach, then do not join as a cadet flying instructor if you want to be a commercial pilot in minimum time. Because there is a bond with SFC, if you join at 23, by the time the training and the bond is over you will be at least 28.