[Nanook]

Last time I was at Changi coming from AMS, it took me all 20 minutes to walk out of the SQ plane, pass the immigration, collect my luggage and went out.
Most of the international fllights arrive in terminal 2.
Tiger Airways and most of the other low budget carriers, depart from the so called "Budget Terminal". Am not sure if there is a shuttle bus service, but by taxi it is about 4-5 minutes.

Like Biofoz mentioned, the Budget Terminal is just a big hall. But you have enough food/drink shoks there and also a couple of free-use internet terminals.