1) That's politics. I understand Singapore and Indonesia recently signed a defence cooperation agreement only to have it scuppered over an extradition treaty (or lack of).
One step forward 2 steps back...
That's the dance we do with our neighbours all the time.
But underneath all that, SAF and TNI have a surprisingly close relationship. On top of training exchanges we have been selling lots of arms and ammo to them including 155mm howitzers. We've even given them some older ships decomm from our Navy.
With Indonesia Singapore decided that it was better to befriend TNI post-Suharto as the new governments are usually foolish, inept, lasts a short while or all of the above.
With Thais it was the same. We were close allies with their military for decades and even gave them a couple of our older F16s. But it backfired on us cos after their recent coup, the (then) new Thai military leader started making things very unpleasant for Singapore.
MAF, OTOH, buys not a single military item from us. And they once even delayed a LONG time before granting us permission to overfly their territory for a sea S&R mission.
That is why the FPDA is slightly ironical in that the enemy (Indon) has become the friend (to SG), whereas the ally (MY) has become rather cold.