Hi lili,
I bring my daughter to school myself, so I have no experience on kids taking school buses. But I've read several threads here where some parents have the same safety concern as you do. You might want to look it up.
Hi Sleuth,
In HK, kids attend K1 when they're 2 yrs 8 mths. At age 2, they can go to nursery which is just like a kindergarten setting. My daughter started going to playgroup when she's 1.5 yrs - only once a week though.
Some people think it's a bit too early to start school at 1.5 or even 2. But my daughter really loves it, and to her, it's just singing and playing with people other than me.