Does Effect Veiler/Swift Scarecrow/Lava Golem's Effects Start a Chain?

My opponent attacks. I use swift scarecrow.

Then can I chain my other trap cards to scarecrow's eff?

Similarly, I chain veiler to an effect. I can chain other things to that same chain link still, correct?

And for lava golem's -1000 burn effect, can I chain to that as well? I've heard varying things, something about it being a maintenance effect?

Scarecrow and Golem are both trigger effects (spell speed 1), and Veiler is a quick effect (spell speed 2). They all start chains.

You can only chain Veiler to an effect that activates in opponent's main phase