Probably but radar range depends on altitude of the radar itself. You can be certain the real specifications of this radar are a closely guarded secret. It will no doubt cover the approaches to Singapore extremely well.
RSAF also isn't going to have all aircraft in the air simultaneously. Aircraft have to be maintained, even when relatively new. 4 aircraft would probably provide regular coverage of 2 aircraft, with a surge capability for a 3rd and the 4th to replace one of the others through the maintainance program. It's radar coverage will thus be mainly shared between it's AEW&C aircraft, maritime patrol capabilities, ground based civilian and military radar systems and sea based Naval radar systems.
Radar range horizons are limited by curvature of the earth regardless of where the radar is mounted. The higher above the earth the further you can see, but then you run into weight, power and cooling concerns, not to mention the mission duration the aircraft carrying them is capable of.
The only realistic way to get constant airborne radar coverage is to invest in something like JLENS.
Raytheon Company: JLENS
Ground and large sea based radars can see a long way because they are usually of very high power (for air search radar systems) but this long range is at high altitude. At lower altitudes their range is much more restricted. Physics have not yet been overcome, no matter how many fanbois like to boast about ridiculous engagement ranges for some SAM systems...
To the F-15's, yes they could do the types of things you mention. AS to whether they can do so from other offboard sensors or radars on ships or ground-based assets, depends on a few different things.
Have they had Link 16 and VMF installed on all assets? Do you have re-trans assets available to network your force over extended ranges?
Don't know enough about SAF to determine that and that information might be classified anyway...
No probs.
